This one isn't too bad, but some songs will take some practice. There are 30 songs in the game. 20 of them took me only 1 - 2 tries to get 5 stars. Another 8 of them took me around 3 tries.
The two that gave me the most trouble were: Kids in America, and Bring it on. Those both took me 5 to ten tries.
The best ideas I have for those two songs is to just keep practicing each move. If you have any other problems, just try adjusting your kinect and the lighting.
One song that people had a lot of trouble with was Surfin' Safari. Personally, I did that one in one try. Just like the above two, keep practicing until you can get it right!