I have a buffer but, before it even's gets a look at it I do either both or at least one of these. Soak in bleach if I foresee sanding it will be long and hard to get rid of the green. Either way I sand them after they seen bleach or not, starting with 400 wet sanding, then 600 and finishing with 1000 (sanding each grit making sure I've sand out the scratches from the previous one). If it's a acrylic I don't go to 1000 but, if it's chewed up pretty good I may start with 220 or 320 dry (acrylic or ebonite/vulcanite)
until pretty smooth then continue with the other grits and then buff with white rouge. If I didn't have a buffer............I'd get one.
There's a lot more too it then just sanding but, to explain it all in detail, for me at least, is a long run out process that I would have to type a long time and probably still not convey exactly how I meant it. :fpalm: