i always try to start with 400grit sandpaper. the lined/marks it leaves are not deep and are easily removed going up the 600/800/1k/1500/2k path. if the 400 won't removed it, but it does remove most discolouration only thing that i need to go lower for is rust/pitting, then i drop to a 220 grit. i don't go lower then that becuase it just takes way to long to get those teeth marks out for a mirror finish.

i go up to 2k (high grit papers are purchased at auto part stores like pep boys) though i think if you stopped at 1500 that would be sufficient. i see the real shine and mirror come out after using a buffing compound followed by maas/simichrome whatever polish you use. for the buffing compound i use fabulustre. bought it on ebay and it works good. its a hard substance and applying it is a tad tricky, i ground a bunch of mine down to powder and apply that with some maas when using then finish with only maas. easier and sticks to the pad easier after ground into powder.

~J