Well I think by looking at your squad you should be able to tell who to keep/release/sell, and you can look at your assistant's recommendation and the coach reports if your not sure. I would look at the potential stars shortlist,
http://www.fm-base.co.uk/forum/downloads.php?do=file&id=108
and set a couple of your scouts to scout the world to look for some gems. Look at Stephen Appiah as-well on a free, along with Davids and Ronaldo. Your squad is good enough already so you should look to buying and developing youth for the future. Also, Pm me if you need further advice, hope this helps!