Try for Appiah and Sorin, they should both be available on a free. They'll provide good squad depth. Other than that, it's really down to you to decide what kind of game you want to play. I'd play Xisco up top as a target man with either Owen or Martins off him. Jonas on the right (much creative freedom) and N'Zogbia on the left. Set them as AML and AMR and set their cross aim to target man. As for the middle, you'll probably need to go with **** and Guthrie untill Barton is available. Back 4 of Enrique, Coloccini, Taylor and Beye should be fine. Obviously Given in goal. If I were you, I'd get shot of Duff, Cacapa, Edgar and Geremi asap. Offer them out to clubs at a little more than face value and they should get snapped up. That'll free up some cash for you to buy wherever you need to. If you have the nuts, sell Owen right off. You'll get about £14m as long as he's fit and that rids you of £125k per week too! Keirrison as a replacement is worthwhile.
You may want to look to buy central midfielders as a start point as I found this to be the weakest area of the team when I started. I'm in my second season with the Toon and my squad is:
GK - ShayGiven and Leo Franco
RB - Paolo Ferreira and Antonio Barragan
LB - Taye Taiwo and Razvan Rat
CB - Martin Caceres, Steven Taylor, Sebatien Bassong and Jonatahan Rossini
RM - Antonio Valencia and Lauturo Acosta
LM - Jonas and N'Zogbia
CM - Nicky ****, Stephen Ireland, Segundo Castillo, Jimmy Bullard and Nakamura
ST - Martins, Xisco, Ivica Olic and Keirrison