last year i bought a second hand onyx guitar for around 150AU and i sanded the paint off and repsray painted it, did a crap job, sanded it off, and now planning to sand everything clean, and give it to my friend whos really good at designing and painting and stuff, except its her first time to try to paint on a guitar, any advices on wat paint to use or techniques and stuff?

and is there like a way to sand very thick paint off, cause i tried sanding the back of my guitar, except all these spray paint lumps got stuck onto it, its there a way to get them off?

thanks, help appreciated =)=)
Spray paint lumps got stuck in the sandpaper? Just tap the paper against something, should loosen most of it off.

For the paint, get an undercoat on it. Then when she paints it with whatever paint she uses put a clear coat over the top. I'm not sure if the types of paint have to be the same though?