Choose your favorite song, best if it has some eye-catching lyrics (especially in the first few sentences). Then make a quick sketch of how you want to apply it to you bag. What kind of handwriting do you want to use? Which colors? Are there any special things you want to highlight?
Mark up to where you want to have your song with a pencil.
Get writing! Don't worry about making mistakes, it could make a nice effect.
Highlight your favorite lines, and add your finishing touch. I chose for hearts. - You're done! Dont forget to let me know for which song you went :)