I'm no expert, but I have painted a few vehicles and found that following the directions/instructions to a "T" is very important! The other note I'd like to make is orange peel can be caused by your paint gun adjustment. Volume of material and spray pattern will depend a lot on the product your spraying. For novice painters you have to learn how to read the spray out. You can tune the gun to your own ability. Check out the tech tip here at Stovebolt for painting. I found it very helpful.
