I'd still recommend the following stages though:
Once your bodywork is ready for paint - a lot of people advocate running a heat gun over the surface and digging out and filling any bubbles that appear - key the fibreglass and filler with 400 grit wet'n'dry paper.
Thoroughly degrease all surfaces with panel wipe and ensure everything is completely dry (this step needs repeating after every stage).
Brush or roller on two coats of etch primer, allowing each to dry and flatting back with 600 grit after each coat, adding more coats if you rub through to the gelcoat or bare fibreglass anywhere (be careful on edges, high spots and corners).
Follow that up with at least two coats of high-build primer, flatting that back with 800 grit wet'n'dry after each coat, not forgetting the degrease and dry stage.
Once you're happy that there are no (serious) defects in the finish, brush or roller on the first coat of top-coat, leave to dry then flat it back with 800 grit wet'n'dry, carefully dealing with any runs or sags with coarser paper (nothing less than 400 grit, though) being very careful not to rub through any high points, door edges etc.
Keep adding top coats and flatting each one back until you are happy with the thickness of the paint and the finish, then flat it back with finer and finer paper - I use 1000, 1500, 2000 then 2500 before cutting it back with a cutting compound (I use Farecla G3). You can either do this by hand or use a machine polisher, just bear in mind it's much easier to inadvertently rub through or scorch the paint with a machine.and doing it by hand in straight lines won't leave swirls.
Finish off with a resin or wax polish and it should look like it's been sprayed.
I'd strongly recommend that you use good quality cellulose paint rather than two pack as cellulose is much easier to rectify if it goes on badly, it will flex with a fibreglass body where two pack will crack and it doesn't contain cyanide like two pack does so won't kill your pets/neighbours/you/etc. I get my paint from Jawel Paints as it's extremely good value and works for me (other suppliers are available. Always use sanding paper wet, never dry, and if you drop a piece on the floor throw it away and use a fresh piece, it's cheap enough.
One more tip - if you're planning to have decals on your car like racing roundels or sponsorship stickers, have those put on before using any cutting compound or polish as they won't stick properly otherwise. (that's from the chap who does my roundels).
All of the above is what I've picked up from speaking to pro sprayers, my paint manufacturer, other enthusiasts, etc., and I'm not a professional paint finisher so if anyone disagrees with this advice please feel free to offer up alternatives.
Good luck, and I hope to see some impressive results soon
) in brush painting, and have never quite understood some of the terms.......
