I'm playing on facebook but I think it's for all platforms.

1. Options:
a)training - more options're needed, there're no possibilities for auto training now.
b) auto subs - now substitution's making only after injured, more options needed here.
c) friendlies - my suggestion's separate official and friendly games, friendlies haven't make any influence, maybe for training but would be training matches then.

2. Friends support
Manager should get some award for supporting, 1 booster for supporting 1 (or 2,3,...) game for example.

3. Exchange
should be more flexible exchange system. You should have possibility change boosters to tokens, skill points and so on.
Support % may be as a gift.