how do you get good on dance central?

Answer 1

You can choose the "Break it Down" option instead of choosing the "Perform It" mode on the last options screen after you've selected a song.  This is pretty much a practice mode, that breaks up the dance into small chunks and has you perform each move multiple times in a row to help you master the motions.  You can also slow down the tempo in order to make it easier to see where everything is supposed to move.  It gives you feedback on how close you are to executing the move perfectly and highlights which body part isn't in the right position.  It doesn't move you on to the next chunk of moves until you have executed the whole section acceptably.  Then it takes you through the whole song at the very end.  Then you are free to "Perform It", or "Break It Down" again.  

And of course, playing A LOT always helps too.  lol