My intention is to have a single thread that new players can read through to get advice. Even the smallest thing can be helpful. I’m hoping that over time, we all contribute a tad bit here and there to keep this post relevant and easy for new players to find.
To make advice easy to find for players, please lead with the specific strategy or audience you’re focusing on (i.e. Farming Advice, Selecting the right SCL, Hoarding/Spending Tokens, etc.).
HP (Hero Points)
Do not spend your HP on anything except for roster slots. This was the first piece of advice I received when I started the game. It was practically invaluable. Later on in the game when you have tons of HP available and have most of the characters rostered, you can start spending HP on other things.
Farming
I will try and go into depth about this concept, so my post may be long and boring, but hopefully will explain this concept better than it was explained to me when I started.
The term “Farming” in this game refers to the process of taking a character from a single cover, to making them into a champion, getting them to the state of becoming a “maxed champion” and then selling them. Early on, and throughout your time playing this game, you will be farming your 2* characters. Later on you can get into doing the same for 3*s and so forth, but that’s later.
My recommendation is that you focus early on rostering all of the 2* characters, with possibly one exception:
The Bagman caveat: Just through playing this game and opening tokens, you will get covers for 2s very, very often, except for Spiderman (Bagman). If you go into “Roster” and look at the 2 characters, you will notice he has the “Limited” tag associated with him. That means that obtaining covers for him is a bit more difficult, as I believe you can normally only get covers for him through playing PvP events (he comes up in special stores occasionally, too, if you wish to spend money on his covers.) For me, I usually get 1 cover for him about every 3 weeks, and I play a lot. For comparison, you will get covers for all of the rest of the 2*s on average of around 1 per character every 2 days or less, although it varies widely. I once got 4 Moonstone covers in a single Lightning Round event, or it can be days between getting covers for them. So, my point being this: most players do not recommend rostering Bagman early on, as he takes up a valuable slot without having anywhere near the progression that other characters do. I’ve been playing about 10 months, have had Bagman about 7 months, and he’s still only at level 119 for me. So when you’re first starting out, he might be one that you want to let expire.
For the rest of the 2*s, though, your early priority (goal) should be to roster all of them. When you do, they will start at level 15. In order to get them to level 94, you will pay, I believe 69K Iso-8 over the course of their progression. Then you will spend another 5K to champ them. So, to this point they have been a drain on your resources to get them to his level. But here is where it starts to get good.
Once you champ them, they start earning rewards for you. For each subsequent cover, (regardless of the ability’s color,) you will get a reward for leveling them up. Those rewards include Iso-8, 3* covers, 3* shards, Heroic and Mighty Tokens, Hero Points, and Command Points. Each of these you will find will be a valuable bonus to have as you build your roster. Eventually, you will get them to level 144, which is when they become “Max Champed.”
Now is when you will want to consider selling them, as you won’t be able to apply subsequent covers to this character anymore. But here are some guidelines for selling them:
Do not under any circumstances sell them before you “max champ” them. I have made this mistake, and I’m telling you not to make the same mistake that I did. If you sell them before they get to 144, you may get, what 12K Iso out of them? That is a bad decision when you consider how much you initially invested in them to get them champed. The rewards aren’t worth the cost until you get them to level 144.
When you do sell them at max champ level, you will get 65k Iso and 120 Hero Points. Remember how much you invested in them earlier? 69K + 5K = 74K Iso. When you sell them at max champ level, you get 65K of that back, which makes the rewards that you have earned between level 94 and level 144 become more of a bonus. This is where the term “farm” comes from. What you put into them initially is almost what you get out of them in the end, with a ton of bonuses in between.
Do you sell them immediately? That’s up to you, but I know many people will wait until they at least get another cover for that character, so that when they do sell the character that they can roster them again right away. This is a good practice and something to consider.
Do you sell them at all? I know having a max champed 2* is fantastic for getting some wins early on in the game, and let’s be honest, you do tend to build an attachment with your high level 2s that you’ve been using for so long. I personally hated selling my 2 Bullseye the first time, as I used him so much with a variety of teams. You don’t have to sell them, but then you have to ask yourself what will you do with the subsequent covers that you do get for that character?
You could sell the covers, but that isn’t recommended at all, because farming your 2*s will bring you far more rewards than selling the covers does. There isn’t even a debate on this, as it is just common knowledge among players that have been playing for a while.
So do you then roster a 2nd version of that character? You can, and some people do, but now you’re devoting 2 precious slots to the same character, 1 for playing and 1 for farming. You can go this route if you’re comfortable with that. Just remember to select the correct one while you’re playing. That’s a mistake that you should only make once. Some people will wait to sell the first one until the second one is champed. That’s also a common practice.
Gotta run, life calls! Hope that helps. 
People have done some extensive work on a new player guide on reddit. Check it out.
Edit: - links to other helpful documents -
Advice for new players: if you ever, at any point, discover that you’re not having fun, uninstall and don’t look back.
Don’t hang around waiting for some potential future fun that may or may not happen.
To add to hothie’s points, you can use two different strategies in regard to rostering and selling your 2* characters.
Strategy 1
In the beginning, consider keeping the fully champed character, Bullseye #1, while you build your second 2* character, Bullseye #2. Once Bullseye #2 is almost as strong as Bullseye #1, you can sell Bullseye #1.
Con: You will need to spend HP to buy more roster slots, but those slots will be put to use in the future anyway, so not much of a con.
Pro: You will have a strong character on your roster to use for events.
Strategy 2
Once you begin using more 3* characters than 2* characters, you can sell your fully champed Bullseye as soon as you get another Bullseye cover.
Con: Any events or battles that requires 2* Bullseye will have you using a weak single cover version of him.
Pro: You can cash in quickly on a character that is no longer as important and use the Iso-8 that you get to champ a much needed 3* character.
Making sense of the first couple weeks playing the game:
https://forums.505go.com/discussion/comment/960604/#Comment_960604
(Rather than recapitulate everything here, I’ve just linked to my lengthy post from several days ago. Note that I am a multi-year veteran of the game but the comments linked above are based on having just gone through the early stages of the game with my daughter in the last few weeks.)
Have fun and explore the different mechanics or abilities of the game. Find the one you love/like. Then, figure out how each character’s abilities synergise with another’s. Do you like to watch tiles getting destroyed? Do you prefer them to be destroyed randomly or do you want to determine which ones get destroyed? Do you prefer to immobilise your opponents at all time? Do you prefer to play defensively or tactically?
Learn to time your moves, if possible, especially for those characters involving x number of turns.
Go for 3* Doctor Strange ASAP, he makes such a huge difference early-mid game.
Alliance: try to find an active alliance. Once you are playing more and if you are feeling good with the game, the resources an active alliance can give are cruzial, so don’t stay in the first alliance you find if they are semi retired.
If you are really active and you are scoring, the majority of commanders won’t boot you.
Ask for advice to them, they should be happy to assist you.
A good commander can difference between a noob and a promising noob so anyone can have his spot just playing.
Just scoring points you will meet the requirements any non top alliance could have.
It is more important to be in an active alliance ratherthan an alliance with a lot of commanders with high leveled champed 5*s however non playing much.
A good way to know you must hurry to exit if in the boss event the LL token is not claimed.
Use Deadpool Daily as a measure of progress. You might at first be limited to just beating the 2* nodes but then as you progress you will start to be able to beat the 3* node and the Big Enchillada. Once you are doing this on a regular basis as you roster the 3* tier with different variations of character teams you can be sure that your roster is filling out and you are getting stronger.
Single 5* covers - DO NOT LEVEL THEM! Not until you have characters on your roster that are also around the 270 mark - this means a maxed champed 3* or newly champed 4*
Whilst most single cover 5* are just meat shields, the exception is 5* Deadpool - if you get the chance roster a single cover and play each day with him to get a free Spicy Taco token that can be spent in his special vault - if you hoard these to 40 tokens you can also be sure to get a specific 4* cover from the vault (the vault rotates to a different 4*)
Progress slowly.
Only buy Hero Points and the SCL level pack deals if you think you can afford it. Otherwise wait for enough HP to roster new characters before you pull elite or heroic tokens.
Most tokens never expire. Covers dying on “the vine” do expire. Tokens can be more valuable.
Favourite 3star Dr Strange and 4star Polaris. They are the single most useful pve and pvp characters in their respective tiers imo. Once you get them at 13 covers
Ironman 40 is the best partner for Strange.
Rocket and Groot (4star) for polaris.
Single covered 4s are usually weaker than fully covered 3s at the same level.
Same for single covered 5s vs fully covered 4s of the same level.
Tokens
Only use tokens that will give you covers for the level you’re at. For example, if you are working on 2* characters, use Standard Tokens, but hoard the rest. They won’t disappear. This will prevent you from getting a higher level cover with no roster slots available for it. I know, it’s tempting to use them, but the thrill of opening new packs will quickly be overtaken by the frustration of having to sell those covers for lack of room. Sure, you’ll get iso-8 for selling them, but in the end keeping a 3* or higher cover to build a character is more valuable than selling it right away.
And when asking for advice try to listen to it and not just ignore it. That is getting so old.
Farm or no?
Farm if
You like to collect,
You don’t mind playing the long game and having your hard work paying off months or years down the road.
You like to be prepared for as many events as possible.
Do not farm if
You only want to spend your time on your favorite or the best characters.
You want to dominate and win now.
You are not interested in investing time into every event.
It should be noted that if you choose not to “farm”, apart from Champ rewards you are also shutting yourself off from some significant Milestone rewards that come from promoting 2* (and higher) to Champions and it is easiest to do this at the 2* level where covers are abundant and characters can be maxed out reasonably easily. However the longer you play, you will eventually naturally max out 3* which is when you will need to make a decision on how you wish to progress with the game - it can be a difficult decision to sell a maxed 3* but hopefully you are at a point where you now have a 4* roster that carries the heavy load.
I don’t currently have any maxed 3s, although I have several that are in the 230’s, so not too far off. At this point, I don’t think I sell any of my 3s when I do max them out. I’ve been playing for about 10 months, so by the time I do max out some of my 3s, I will have a year invested in them. I plan on rostering a dupe and farming that one, but keeping my original max champs for events where they are the featured character. Maybe that will change as my iso debt climbs and the temptation becomes stronger, but to me it’s different than 2 farming because for a 2*, you’re spending what, maybe 6 weeks to max champ them whereas for a 3* you’ve got a year invested in them.
Now, I may have a different shard strategy than other people do. You could max champ a 3* faster than I do if you focus solely on that one character with your shards, but that’s not what I do. I spread my shards out to whoever has HP coming up soon, so I level up most of them at about the same rate. And maybe mine isn’t the best strategy, but I do have 200 slots from chasing as much HP as I can this way, as I hated letting covers die on the vine early on in my playing days. That doesn’t happen to me anymore, partially because I get the HP to roster them before they expire, and partially because I wait until I can roster someone to open LL tokens and such. And also partially because I have most of the characters in the game by now (only missing 35-ish 4 and 5*s combined), so opening tokens is more likely to give me covers for characters that I already have.
Anyway, like I said I’m still early on in this game as compared to other players, but I don’t see myself selling maxed 3*s until I can max out a dupe and sell that one.
I originally was also reticent about selling max champ 3s but one of the reasons I ended up doing it is because farming the 3* tier is an expensive business if you start to roster dupes. Unfortunately the best 3* rewards are generally back loaded and 3* covers come thick and fast so having multiple dupes progressing at different stages keeps the rewards rolling in which requires a commitment to extra slots - I have 37 slots for farming but of course even that isn’t enough to fully farm the tier. I don’t sell all my maxed 3s and have most of the 3* maxed out but every now and then I will sell one if I have a dupe in reasonable shape.
I only have 3s maxed for LR. The others are continuosly climbing up and down as I have a lot of characters better than them.
For my LL tokens, HP, iso, 4shards are a lot more precious than the 3* himself.
Now the puzzle gauntlet can be troublesome without them, though.
My advice is only to sell 1* covers, the others for farming.
I’ve thought about that, keeping the maxed out Lightning Round 3s, as those don’t change. And I see a lot of maxed champs during the Lightning Rounds. So I will definitely keep those, as I use them weekly. And you’re right, sometimes the Puzzle Gauntlets work better with specific 3 characters.
It’s a bridge that I haven’t crossed yet, but will be soon, so I definitely listen to the advice and experience of those who have crossed that bridge. I guess I’ll see when I get there. And Daz is right, the extra slots required for farming I can see as being expensive and time-consuming to manage. Maybe when I get a dupe champed I’ll reconsider with some of them.