opinions will differ, but this is what works for me: if you use PPG products, base/clear or single stage urethane, and if you let the paint air dry, 24 hrs should be long enough. If you wait much longer, it will be much harder to sand and buff the paint. I tape all edges and high peaks with masking tape, wet sand area with 1000 grit, then 1500, then 2000 (a little soap in the water helps also) until all the orange peel and surface debris is gone. This can be detected by wiping the sanded ared dry to see if any "shiney spots" still appear on the surface, if so, keep sanding. Let the sandpaper do the work, you are not rough sanding at this stage, dont get too exited and work it too hard..if you break thru the clear coat or on a single stage job, thru the paint to primer, you have just screwed up...When you have everything sanded to suit you, wash everything with soap and water. Once everything is clean, I use a CP pnuematic buffer with foam pads(different color pads for different degrees of buffing, heavy, medium, light, etc.) The pads are color coded and state on them what cut they are for. I use a buffing compound called "Production", it's pink kinda like Pepto-Bismal...do an area no larger than about 3'X 3' at one time. Keep buffing that same area until it shines like you want it. After you have done the entire car to your satisfaction, then you can use swirl mark remover (PPG, MEGUIRES, etc) to bring the shine to top shelf appearence. This is a long, drawn out, hard work process, but the end results will be worth it. If you dont have a high dollar paint booth, this is about your only salvation, as much work after the paint as before the paint. But it will make a distinct difference in the appearence of your paint job when you are complete. Hope this helps...PACO