1) Enough players to fill your most used formation and at least 2 sub in def 2 sub in mid 1 sub as ST
2) Recommended 4-5* star player
3) Buy most expansive and young players (as they train fast) so they last 3-5 seasons
4) don't change formation a lot during game
5) fill squad rest space in squad with free agents sell them by end of season with any unwanted players(poor performance)