A few weeks ago YouTube released a creators guide for musicians who use YouTube. There are a lot of points worth noting amongst those 40 pages. If you'd like to know more about to get the most out of your YouTube music experience but don't have time to do all the reading, check out the 9 highlights Jesse Cannon outlines on Music Think Tank.
Ask fans to remix, cover and create videos with your song involved that will help it to spread. While this tip is often utilized, the difference it can make is often underestimated.