I've used many guns and systems over the years. I've gotten the same results with a $40 Harbor Freight gravity gun as I did with a $600 DeVilbiss gun.
I really like using the 3M accuspray setup. disposable cup liners and Lids, disposable nozzles, only have to clean the needle. I've gotten lazy and crap in the gun and it acting up with a fresh load of paint makes me chain together curse words....
This kit comes with everything you need to get started.
https://www.amazon.com/3M-26580-Accu.../dp/B001UNZIP8
Whatever the paint system you choose. make sure the etching primer, color coat, clear coat (if you're using one) are all the same brand.
On the sanding: 320 random thru the clearcoat, 400 block sand, etch primer, 400 block sand, Topcoat light coats till all areas have no flash edge, wait 10min between. You should have no orange peel.
If you do have some, wet block sand 400 or 600 till smooth. same sanding if you're going to clear coat it.
The goal once done it is have a finish that will not need compounding and wet sanding to look right.
Eastwood has some pretty good how-to videos and decent paint systems.
https://www.youtube.com/channel/UCMb...Kx-zKDchXjeNfQ
https://www.eastwood.com/
Last thing, you should build a tent to prevent trash from causing you to throw things.