As many others said, more realistic transfers.
1: Computers get their transfer bids accepted for considerably less then you.
2: IE: Paulo Di Canio feels the both of us can become friends... Can we have that option then? For friends and enemies?
3: I would like more jobs, I know it's called football manager and all, but what do we use the money we get for? some guy before me suggested to become an owner of a club, thats a totally brilliant idea, it's better, in my opinion, then buying a house etc etc etc.
4: More realistic matches: IE, Skill moves, more realistic Shooting/Passing, and please, the goalkeepers. One time, my shot was going slightly wide, the goalie pulled it to him, and then when he was about to save it, it went in the goal.
5: More facilities, we get things like money from fan sales etc etc, then why not we have a factory + fan shop or something? Like you can also build stuff such as a Hotel?
6:Good and Bad Reputation: This is a weird idea, but why not good and bad reputation? Good reputation gives you a better chance of having a takeover, staying in the job whilst the takeover is completed, bigger players coming to your club for less if the reputation is high enough, and bad reputation does the opposite for all that, you get good reputation for winning games, leagues, cups etc, and bad for doing the opposite, getting relegated, losing out early in the cups etc.