If you have dirty chrome, clean it with lacquer thinner, acetone, or wax/grease remover with a soft cloth. I have attempted to polish chrome using a small buffer and glaze (not polish). The chromium layer is really thin and it's easy to go through to the copper, really easy. I had no choice and knew I had nothing to lose. You can use glaze and lightly buff by hand that's pretty safe, just make sure the glaze isn't polish because it'll scratch easy.