For the next little while I'm slowly going to post answers to your most frequently asked questions. If you have something you'd like covered - ask away! My email address is firstname.lastname@example.org. If I don't know the answer to something I'll either try to find it, or confess that I don't know. :)
Q: What type spray gun would you recommend?
I use this gun, but one this pricey isn't necessary for a great finish. I actually wouldn't recommend it until you've used a less expensive option for a while first.
Spraying is one of those things that requires a bit of skill and practice to perfect. Even if you have great brushing skills, you kind of start at ground zero with a gun. Regardless of the set-up, a faulty application can leave you with drips, steaks or improper curing.
Q: What size tip works best?
I would recommend purchasing a separate tip anywhere from a 2.0 to a 2.5. The size used always depends on the viscosity of paint being used.
Most spray guns come with a tip that is too small which results in a sandpaper like finish, loss of sheen, frequent clogging and a lot of disappointment. Sounds awful. :/
When a spray gun advertises that it sprays lacquer, oil, etc. with a 1.3 or 1.5 tip, even a 1.7, it's referring to a clear coat. Pigmented paint is much too thick to properly spray through such a small opening - a clear coat is not.
If the paint is thinned enough to properly spray through a small hole, the quality of the paint is most likely being compromised. Thinning is great and often necessary, but only to a certain point.
The good news with a large tip is that the settings on a spray gun allow you to close off the opening to allow for thinner materials. A small tip, on the other hand, cannot be made larger.
Q: What about pressure settings?
Pressure settings depend on many factors - two of the biggest are your particular set up (gravity feed, airless, airless assisted, etc.) and the viscosity of the paint being used.
It's hard for me to give specific air pressure numbers when they depend on the type of paint I'm using and that changes from project to project.
The biggest tip there is just to play around with the settings and do online research for your specific set-up or paint.