For polishing the frame, I would use a mild automotive polish like a dupont polishing compound. Take it very easy and the Sierra brown paint will pop back to life. Too much compounding will change the color of the bike. There's a brown coat over a silver base. Then seal it up with wax. The polish will also brighten up the decals.

The Stem and bars don't look bad. I would use 0000# steel wool and mothers mag & aluminum polish.