I'm self taught, and here's a few basics that took me years to figure out.
-If you have a panel with 2 or 3 small imperfections, don't try to fix them all separately. Skim the 2-3 dents with filler and sand smooth so as no metal shows through between them.
-Buy a gear driven mud hog!!! This has saved me countless hour of tedious sanding. With 40 grit paper this thing will get a panel perfectly flat.
-This is my best kept secret!! USE A SPRAYABLE FILLER ON YOUR FINAL COAT!!!!!!When you have your panel as straight as possible with body filler, a coat of this will make it perfect. I block sand this stuff with 100 grit, then finish to 320. My high build urethane then goes on top.I have pictures of my car that I just did at home on my website.If I can do it, anyone can. It's not rocket science it just takes patience.Dan