A mother's buff ball on an electric drill is the way to do it. Just pick the right polish for what you're polishing. You can also use this for polishing up aluminum nerfs, bumpers, grab bars, wheels, etc. Just use chrome polish for chromed steel, use mag & aluminum polish for the aluminum parts, etc, and don't try polishing something that's clearcoated. The only brand I ever use is Mother's, it's a little more expensive than some, but it's the best sh*t out there PERIOD. I'll look for a couple pictures of aluminum stuff that i've polished by hand with mother's polish, it looks like a mirror.
Using sandpaper is a real sh*tty way to polish anything. Especially chrome. It won't take long before there's nothing there except raw steel and rust.