Well, if you have a HVLP spray setup, then you should know the basics with paint, which is it's all about prep. 90% prep, 10% actual brush, roller or sprayer in hand time.
Under the LWL you have two choices; anti-fouling or not. If the boat is moored or spends more then just a day or two at a time in the water, you need anti-fouling paint. Assuming your hull is 'glass and painted before, all you most likely need to do is scuff up the previous paint and apply more. If not, then you need to scratch the hull pretty good with 120 grit, then prime, then paint with an anti-fouling paint. Anti-fouling paint comes in a variety of "flavors" and you'd be best advised to use what everyone in your area recommends, as they do seem to have formulations that work better in some places then others.
If your boat will be kept on a trailer, then you can use a single or two part paint under the LWL, knowing that it's not designed to remain immersed for very long.
Topside paint can run the gauntlet from $30 a gallon acrylic house paint, to $300 a gallon LPU's. You generally get what you pay for with topside paints. If you want high gloss retention, high durability, hardness and scratch resistance, then the solvent based LPU's will fill the bill, though they can be difficult for the novice to paint and will be completely unforgiving if the surfaces aren't smooth, fair and the painting conditions reasonably controlled.
This brings back the prep issue again. There's absolutely no sense in spraying a fine quality paint, over a surface that looks like it was faired by a punk rock band with a wire brush. These high quality spray jobs are best left to those that have the ability to truly smooth and fair a hull, plus apply the paint in such conditions that fish eyes, bugs and dust aren't more numerous then the metal flakes in the paint itself.
My point being, a good quality paint will look great on a well prepared surface (only), if applied correctly. On the other hand, if you want ugly, then apply a high end paint finish over a poorly prepared surface and you'll quickly wish suicide wasn't so hard to pull off. By ugly I mean shinny and you wish you didn't have to look at it; like having your kind souled, slightly Alzheimer's laden, 89 year old, formerly well endowed, aunt Mable, accidentally dropping a boob on the diner table next to her Thanksgiving Day plate of turkey, kind of ugly . . .