Need help with roster

  First I guess that you are not including 2*s that you have rostered?  If not I would highly recommend starting with them first.  Roster and champ them all, or at least the really good ones and then start with your transition to making some 3* teams.  

 I copied and pasted this from a similar type post so hopefully this can be helpful for you too.  (Because the search features for these forums are imo not very helpful)

1)  Make sure you only have 1 max champ in the 1* category.  Iron Man 35, Spider-Man or Juggernaut are usually the more popular choices.

2)  If you haven't already, look at these posts so you can get an idea of what people say are the best 3* or 4* characters in the game.  https://forums.d3go.com/discussion/67654/all-the-different-character-rankings.  I was really helped by Dauthi's 3* guide when I started and I would recommend you start there.  Keep in mind it hasn't been updated in awhile, but to be honest there's been no other 3* that's come out since that's going to be in the top tier.

3)  The way I used to manage my 4* covers is I would look at the DDQ schedule.  https://mpq.gamependium.com/ddq/  When a 4* was required in the Behemith Burrito, and I had the 3*, I would try to hold onto the character until they were required for that node.  Then discard it when it was no longer needed.

4)  Take a look at the sneak peak section in the forum often to see which 4* is going to be required in upcoming PVE's.  https://forums.d3go.com/discussion/69833/mpq-sneak-peek-january-2018-edition-updated-1-24-18/p1.  You'll have a much easier time making full progression in PVE if you have the 4* required for the event and once that character is used, you will not need it for a long time to come, so you can probably get rid of it if it's not an overall useful character (an exception is with new release 4*s)  The 4*s you do have so far are pretty good ones but just keep in mind that they're not going to be very helpful for a long time out, unfortunately.

5)  Any character that has a 3X chance of being pulled I would keep.  You're more likely to get more covers of characters like Nico, Rogue, & Rocket and Groot because you are more likely to pull more covers of them.
(Hit info "?" on Heroic or Elite tokens to see which characters are currently at 3x odds.)

6)  Don't pull any tokens like classic or latest legends that only give 4 or 5*s until you have most of your 3*s rostered.  Once you have more roster slots available you'll be able to start getting more covers through those tokens.

  My personal favorite 3* teams were:  Rocket & Groot (insane healing and decent green damage), Dr. Strange (team healing one of the best stuns in the game), and IM40 (one of the best AP generators in the game).  And my second favorite 3* team was Iron Fist, Luke Cage, and Scarlet Witch.

   It sounds like you are only opening standard recruit tokens?  Those are mostly going to give you 1*s more than anything else.  The ones that will really help your roster are going to be the elite and heroic tokens, they guarantee you a 2* at least and sometimes a 3* and very rarely a heroic token will give you a 4*.   Those are the ones you want to collect by playing story mode and versus.   

You need to play prologue/Story mode to get more different tokens.