I found that most polishes left a white residue in them after cleaning so they show up more.

I then started using Poors Boys black whole glaze, and natty's past wax, both designed for darker cars and they work a treat. Well worth trying these products as they are cheap, very easy to use and will help make the stone chips less noticeable.

If you can, then do a proper clean on the car first including a clay bar sessions - again very cheap to do but makes a HUGE difference, the paint will be super clean and smooth and polishing is much much easier afterwards. Plus you then aren't polishing grit into you paint.