It really is best to do that. Also, you should always (literally) feel the rhythm of your work right before you start. If you don't have a solid idea of what your works "rhythm" is like, put in some DJ Premier (seriously, the man has some mind-blowingly funky songs!) and find the song that is the most similar to what you feel like at that moment. If you don't like hip-hop, then I'm sorry, but it's as true as unbelievable it might sound: Graffiti and hip-hop are simply inseparable.