SingStar Hints for PlayStation 2
Also on: PlayStation 3
Im not sure that there are any cheats for the game but here is a hint.Some times you can not sing very well to some songs but you want to set a high score to fix this insted of singing you could hum to the song.You can then get more points and seta higher score.
If you don't know the song just hum in tune and your points will raise. If you also sing in a higher pitch you'll get better points as well.