Wet sanding starting with 800-1000 grit paper (depending on how smooth the finish is to start with), 1500, then 2000. If you need to level sand first, start with 500 grit. Finish with this fine polish...
The key to sanding is to sand very lightly, ONLY as much as necessary (it is VERY easy to sand through your clear coat then, best-case-scenario, you have to start all over again), and to make sure you successively remove all of the "scratches" left by the previous grit paper.
That's very possible, especially if you dry sand. Even wet sanding you need to go to at least 2000 grit. And like I said, you need to make sure each step removes the scratches of the previous step.