What's the best way to get scuff marks off the fuel tank?

Scuff marks, like light scratches? Use a rubbing compound. Go easy with it so you don't rub the paint or the clear coat off. It is an abrasive. Follow the directions, use a wet rag, then wipe it off right away. Then apply a polish to the tank. Should take them off unless you've scratched the paint to deep. In that case I'd take it to a paint professional.

Wayne :)

I need to do this too - previous owner had a tank chap as well as a fork bag (without protecting the fender) Both clearcoats are scuffed. Thought about wet-sanding the clearcoat (yes, the scuffs are that bad) but I'm a little afraid to try...

If you try, and it works, then you've lost nothing. And if you try and fail, then you'll have to have it re painted, as you probably would anyway, right? What the heck. I'm gonna do a paint job on mine this winter. If it looks good, great, if not, I'll take it to someone and have it done. No pain, no gain.
Wayne :)