dont buy any stupid things, like Basic Characters (pointless really, i regreat buying Viper). Dont buy any weapons that are already available in GP (G36, Scar, AK, L9, so on).
Dont buy ANY of the hats or camos.
Do buy Gp Crates, Weapon Crates, Name Color, a knife, AND DO BUY THE M416 CQB! its beastly.