Is there a guide somewhere perhaps suggesting the easier NPCs to beat first to improve your deck?

I'm a brand new player but I remember Triple Triad from FF IX. I went to play in game, earned a few 3 star cards, and then it tells me I can't put them in my deck because I have too many rare cards (apparently more than 1 is too many).

I don't recall some of these mechanics like Plus (though I haven't played FF IX since it came out ages ago) and some of these NPCs have tough decks to beat. I presume you need to progress from easier opponents to tougher opponents, but I don't where to start or what that progression should look like.