I need advice for madden

Could you please be more specific?  Start working through your Challenges, there's an awful lot to choose from these days.  Immediately dive into the BHM (Black History Month) challenges the moment you are feeling comfortable enough, as you'll get five really decent cards that get team chemistry with everyone/anyone.  From there, some combination of Legends (work backwards, starting with the most difficult you can beat).

Don't miss your dailies.  If you only do one thing when you log on, make sure it's:

1. Gain 200 yards on offense
2. Purchase a pack
3. Create a set

Each and EVERY single day, it's imperative that you keep up with these if yer hoping to build out that squad.  Which game modes do you prefer?  Some folks are heavy into H2H, i'm more wired to enjoy the Solo battles, but hop around a lot.  I'm fairly new myself, started around Thanksgiving.  I do not want to encourage anyone to pony up real money for packs, but i ultimately broke my own rule, because it added an immense amount of fun factor to my grind to be able to have a full squad of 49ers.  Please feel free to draw some inspiration from my team here.

If you have any specific questions as you're getting started, i'll do my best to address them.  I'm running a lot of man to man press on defense, if you only notice or prioritize a single attribute, look for FAST (speed) players.  It gives an edge above almost everything else, at least in my somewhat limited experience.  That's how i structured my team.

Managed to track down a slightly older (from a ~week ago, i've made significant progress in that time) roster dated February 8th, which will better demonstrate the mish-mash of players i had prior to going full 50/50 49ers theme team.  This might be better or more informative for you than looking at the first link above.