random orbital is what I use, ordinary orbitals leave horrible swirlys behind. I only use that for the initial sanding and switch to hand for the lighter grits. I didn't grain fill my Tele, took quite a few heavy coats of primer to get it to glassy smooth. next time I'll grain fill, it's cheaper and quicker than endless coats of primer. I used car acrylics but in a spray gun, I've used cans on other projects with no probs except they can get a little expensive but still....cheaper than a compressor.