Here is a list of some of the best players you can have on a team:
Goalkeepers
Tim Howard
Iker Casillas
Defenders
Rio Ferdinand
Paulo Maldini
Alexandre Nesta
Roberto Carlos
Lilian Thuram
Sol Campbell
Midfielders
David Beckham
Zinedine Zidane
Cristiano Ronaldo
Luis Figo
Ronaldinho
Edgar Davids
David Bellion
Forwards
Thierry Henry
Ruud Van Nistelrooy
Ronaldo
Del Piero
Shevshenko
Adrian Mutu
Hernan Crespo
Get the best players
Go to options menu, then Player Swaps. Swap all good players to the team you want to play on, then save that as a squad. Go to New Season and select Current Squads and choose your new team.
Easy way to win
Pick your side, then during the game hit select sides. Now move the controller under the opponent's side and resume gameplay. Now you should score as many goals as you want (while under the opponent's side), then switch back to your side again to finish the match with a huge score.
Buying players
If you intend to purchase a player, bid about 1 or 2 million above asking price. Here are some of the best players you can buy:
Thierry Henry
Ronaldinho
David Beckham
Ronaldo (either)
Tim Howard
Roberto Carlos
Alexandre Del Piero
David Bellion
Ruud Van Nistelrooy
Hernan Crespo