Spray painting tips needed!

Okay, I have a hope chest that is like 11 years old. I want to paint it black, but it has a glossy finish. I also plan on reupholstering the seat on top. Does anyone know anything about spray painting glossy finishes? Is there a type/brand that gets the best results? Will I have to sand it or is there a way to paint/spray paint right over the existing finish? Any suggestions would be greatly appreciated!