I try to go for South Americans and Africans, and always try for unknown players (I do sign the big names, but I much prefer great players who aren't well known).
Couple players:
Lauren: Cameroon - Well-known only because of his free-transfer status at the beginning of the game, this seasoned right back may not be Srna, but he can **** sure play like him when he's in good form. First year for us at Villa, he performed better than both Habib Beye and Luke Young. He's got one or two good years in him still.
Mauricio Pereyra: Uruguay - Amazing youngster, and an insane passer. This midfielder spots passes better than most seasoned and intellectual midfielders. Gets amazing assists, and his passing is so pinpoint accurate that it's unlikely he'll lose the ball through those means. Only 19 at the start of the game, and already in the Uruguayan national first team and making frequent appearances.
Edixon Perea: Colombia - Not the perfect striker, but he does his job and has an epic name to boot. Doesn't score like mad, but his goals can be influential, and he's always a great player to have supporting a better goal scorer. Also, free transfer at the start of the game, just sweetens the deal.
Dušan Kuciak: Slovakia - Superb Slovakian goalkeeper, he replaced Freidl and Guzan as soon as he got to the club at the beginning of the second season and has remained there.