If you’ve never made roses from gumpaste or modeling chocolate, I highly recommend this three part tutorial. She uses gumpaste, but you do it the same with modeling chocolate. For me this is the easiest, fastest way to make them and I think the roses come out looking very organic. When you make them one petal at a time they tend to look spirally.
http://www.youtube.com/watch?v=c6teAcewmZY