Mural painting question

[kickandslide.livejournal.com]

Has anyone here ever painted a mural on a bedroom wall before? I am being comissioned to do a mural and I just wanted to double check what kind of paint to use. Should I use small cans of regular latex wall paint in the primary colours and mix them on site?

Also, when I draw the design on the wall, should I just use pencil? or is there a better tool that won't bleed through the paint?

Thank you!