6 it's what I use
6 1* players
+ 8 5 to 6* players (good performers + fast trainers if possible)
+ 7 5* "mercenaries, bought and sold in the end of the season (must be careful and don't give them the 6*, so try to sell them before the new season)
+ 1 empty position for the academy player or some good opportunity
please post a picture of your team