Best time to sell players and should i buy new players ?

[Matteo de Clemente]

That's the right way,so you exactly know how your players may be used to face your opponent teams.

I change a player when:

1) he's going to get retired (of course) or he has nothing more to give in my team (even if he's young and 5 stars rated)
2) he's over 25 and his training power is too slow
3) his quality level is substantially no longer good in the new season.

Managers who operate like you,can analize all aspects of your players,choosing them for the abilities they need by a player (they'll really try to make a good bid ..)