Hey! Welcome to the forum!!! I'm 17 too, and I don't have the half of the equipment that you do . Don't folloy me yet, wait for others (like LGM itself or Maiden69) but, I've painted and finished until now two guitars (and I'm making my own now). I go through this:
- Sand the body from 80 grit and progress to 320;
- Apply a sanding sealer (I brush varnish... medieval huh?! );
- Sand again with a 320 grit;
- Apply the paint or burst you want (rattlecan or brush itself...);
- Scuff sand with 320 grit paper;
- Apply the finishing coats of VARNISH with BRUSH (at least, in Brazil, they are very good! Half polyurethane compound... big shine...); apply 2 to 3 coats a day, and wait two hours between them;
- Flat sand with 400 grit;
- 3 coats again;
- Flat sand with 600 grit;
- 3 more coats...;
- Flat sand with 800 grit;
- Buff with buffing compound (the hard one), can be made by hand (I do...);
- Buff with the medium compound (gives a great mirror and shine surface);
- If you want even more gloss, buff with the fine compound!;
Well, hope it helps you dude! A small note on "flat sand": you should sand until no "shiny spots" are visible! Well, c ya!