Resist painting over them if you can. If anyone ever screws up a paint job it's usually the clear coat, especially clear coating over decals. If the paint is a solvent based paint you can get by if you lightly dust several coats. If it's a two part paint, the reducer or solvent will eat the decals unless it's dusted very carefully and even them it's a risk.

Don't paint them. Mask it and paint your own.