Since the first championship manager I have been trying to find the best formation it took me a couple of years, but I found that the best one is 4 in defence, 3 in midfield, 2 in attacking midfield (centre) and 1 striker.

And here are some great signings:

Freddy Adu (free)
Tevez
Ponzio
Richards (after 1 season)
Rruben
Kim Kallstrom