Orange peel is the result of too much pressure, wrong thinner to paint ratio, too large of fluid tip, miss adjustment of gun, and maybe even operator error. Choose the solvent/thinner to match the temperature. In my business we had a commercial paint booth with an assortment of spray guns from several manufacturers. Mostly Binks & Devilbiss (Same company!) . The most used were pressure fed HVLP Binks. Minimal overspray. Keep the booth air drawing the overspray away from the already coated area. Don't spray like you are dusting the area. Keep a constant wet line and don't go back over any area already sprayed. For small parts needing one off color we had a Mac Tools HVLP gravity fed gun that was given to me by Mac. It's small size is an advantage on complex shapes. Model SG1300-14 1207. They are cheap. I've kept it for my hobby use. It works fine but is no match for the production guns. Those cost many hundreds of $.
What ever you do, keep it clean! Don't let anyone else near it. Never use any metal objects to clean passages, they will scratch the openings and distort the pattern. It's way more about the operator than the gun. A coalescing filter & desiccant drier is a good idea for paint air. Are you going to clear coat? Remember the time/temperature sensitive recoat time!
As you can see, likely getting way too expensive for hobby use. But if you want it to look like a new car..... Surface prep is a must. If you put too many layers of primer surfacer on it will form a weaker, more easily chipped paint job. Get a tube of glazing putty to avoid trying to fill scratches and minor blemishes with layers of surfacer. Practice on scrap before the real thing.
Alternative: take it to a body shop! Yes, I know not acceptable for a hobbyist.
