I had the same thing with a cello, what I did was buy a can of spray paint that was primer. Otherwise as long as your spray paint isn't gloss you should be able to paint on top of it. There is also clear spray paint you can buy once you are done, and use it as a seal etc. (it also adds a really nice glossy shine)
(and of course you could just use acrylic...you don't have to use spray paint [though I really recommend the clear gloss later to prevent from chipping])
