Prime it with a tinted primer. A tint in the shade that your going to paint the room.Any color like that may need a second coat of the finish coat . So you may need up to 3 coats of paint. GL

I'm going to paint my room soon and I don't know how many coats it will take. I'm going from a very bright green (like a green skittle) to Valspar Sea Kiss 5005-9C. Will it take more than one coat to cover a color like that? Or will I need to paint it white first? Thank you!