Ive been trying and trying. personally Im abandoning the sanding method. biggest problem is that it ALWAYS ends up going through an edge somewhere; the paint isnt as thick at the edges and the sandpaper grabs better; you can go right through it in 1 pass if you make a mistake and boom your repainting the car.
when your all done; even up to 12000grit; its rough. Ive tried waxing it after and it helps; but it gets some swirl marks and on something that small; thats devastating to the overall appearance.
I asked here and some said to use printer paper as a sanding paper; that seems possible. I got decent results using a polishing compound also, not perfect but maybe with some practice it was the closest.
in the end I believe what is nescessary is a very close starting point which starts with the painting. if its almost perfect before; it wont need much polishing.
if you want to give the sanding a shot; and feel free, it cant hurt. I believe you sand after the primer to get the highs and lows in the model evened out. then you put down your paint coats which are applied extremely thin of course and about 5 minutes apart or 24+ hours apart(either still tacky, or completely dry). no sanding between because a single coat will ruin that, assuming there are no drips it shouldnt be nescessary to sand between coats.
sand at the end starting low untill its smooth and working your way up with each grit untill each grit has totally removed the last grits ridges and valleys working into smaller and smaller marks till they are small enough for wax to shine it up. watch those edges....