Well i try to look at it from a managerial point, and try to keep it realistic,
for example if i play with tottenham which are a fairly big club i buy players that are available (playing for not so big clubs, or are substitutes in big clubs) that would be realistic for me, also which milan, barca or man utd first team starter would accept moving to tottenham. And the second thing is that i develop a system of play and search for player that suit my play and formation.
Also i buy only players i have seen in real life action (it makes the game more real for me, also i then know what is their style)
My team would look like for example:
Gk: Ochoa (Time for him to move to a bigger club). Rb: Ilsinho (same here,and with this guy you need no winger he's up there in attack all the time),CD: Barzagli (this guy is phenomenal, he would keep the defence together),CD: Ivanovic (Great defender also young so he's going to be only better),LB Maxwell (inter has a lot of LB's so they woudn't mind selling also he would be promised a first team spot)
For the midfield i need two fast runners and good ball suppliers one hard man and a playmaker. For a hard man i would go for either Keita from sevilla or sissoko from liverpool who hasn't seen much action this season, playmaker v.d.vaart or diego both available and maybe young but great nasri from marsellie, but i would go for out of favor Tiago from juve who can take long shots helps out in defense and is a good ball distributor but he would then be partnered with kim kallstrom rather then a CDM,also there's luka modric a guy of equal talent to those three just waiting for a transfer out of dinamo zagreb but they're not in the game so... , and for a right winger i would take kader keita from lyon this guys is simply outstanding i saw him in his lille days and he was a beast, and for the left i would buy simao from atletico he's an intelligent player and a good passer and crosser , for attack i would go for one of these: pandev, huntelaar, sanogo, cisse,fred, vucinic or amauri (all have similar type of play like crespo or drogba they're only thinking of how to get the ball in the net) and one of these two not intentionally both argentinians Aguero or Lavezzi (players like rooney that are more comfortable playing as a supporting striker and playing in the hole, these are my most favourite kinds of players) In attack i would most probably go with Amauri and Aguero, or Vucinic and Lavezzi.
I know i went a bit overboard
But my girlfriend doesn't want to hear a word about football so i'm gald i could at least here say a bit about how i play fifa
so my current career I've jumped into the deep end and started with Bolton in the Prem (big surprise, I know) and I've sold the want-away players - Diouf & Jussi, as well as Nolan and a few others and have gone for young brazillians mostly to add a little something to my squad, while dramatically lowering the average age of the team. The loan system has proven very helpful, as have the free agents.
agenham&Redbridge, Manager Mode:Morecambe. Working on this, sotigris !