I'd work up to 2000 grit finishing paper, then use Meguiar's Ultimate Compound or Swirl X, depending on how much cutting action you want/need based on the haze you're seeing. Start with a good sanding block and get your wet sanding going by working the high spot down. If you did 600, then move up to, say 1200 or 1500 then up to 2000. Once it is basically level and smooth, it's time to take the dullness out with a good polish.
I believe the Meguiar's Compound is more aggressive than the Swirl X is. You need to make sure you have a level surface to polish, which is the job of gradually working to 2000 grit finishing paper from the 600 you already have done. Work slowly and check often throughout. I've used NuFinish clear scratch and swirl remover too, but it seems a little more aggressive to me (though the NuFinish is nice for removing actually scratches). It's important to follow the polish directions as far its abrasives are concerned- the better ones tend to require letting them dry a little into a haze then do your buffing with a soft cloth. You can always remove more, but it's hard to put material back.
If you're working on a very small area, you may want to also look into what are known as "Micromesh Pads". They basically combine a sanding block and sandpaper into a single unit on a very small scale. They're small, soft pads with a plasticized sandpaper surface, with grits going all the way up to 12,000. You can get them at woodworking type places. You can use these instead of a sanding block if you're working a very small area. Then you polish and finish as above.
