5th Street Pub

I'm in an art class where we are encouraged to experiment. I have an old metal "No Parking" sign that I was thinking of using as a canvas. The letters are raised, and I think it would look cool to paint a portrait or something over it. The metal is probably similar to a license plate, but thicker. The sign is already painted, and it's in good shape... No rust or anything. I just don't know if I need to strip the original paint first or prime it with something or what. I also don't know what type of paint I'll need to use -- right now I've just got a lot of acrylic paint, but I have a feeling that acrylic paint would peel off once dry. I could go buy some more materials if I need to. Anyone done something like this before?

I am looking for some contemporary bar stools that will match a metal silver pub table I have