There are (at least) three major components to doing a paint job... 1) the disassembly and reassembly of stuff from the car (door handles, front grilles, etc.); 2) the prep of the car (rust repair, panel straightening, primering and sanding); and 3) the painting of the car (usually the base coat and the clear coat).
You can switch some of the items around, but I lumped these together because of what you were willing to do...
If you go with doing the first two yourself (in particular, the second one); you will want to make friends with your painter, because most (good) painters are very concerned about what is underneath their paint; because any number of factors can ruin a paint job - improper prep of the painting surface; incompatible primer and paint; improper (incomplete) mixing of plastic body filler (I hate the word bondo); thickness of bondo (er... plastic body filler) - (e.g. too thick); etc. etc. etc.
I would strongly suggest taking a night class at your community college on body repair... You may get to work on your own car as your semester project and you can learn what to do and what not to do. And it is like $60-$80 for the semester.
But like I implied, don't be surprised, mad, or upset if the "paint man" doesn't want to touch your job (without doing the bodywork themselves.)
Yes, you can save big bucks if you do it yourself (90% of a good paint job is the prep [both time and quality]) - but realize that it is a "relationship" between you (the body man) and the paint man.
Plus, and this is the reason most of us are on this board, we enjoy the process of restoring (the best of our ability and toolsets and facilities) our cars.
//Mark