I have done around 30 stencil jobs on my games, customer games etc so far. I have used stencils from Pinball Pimp, cut my own, Classic Arcades, Twisted Pins and Pinball Pal. Here are a few things I have learned.
I make my own stencils for games I paint frequently or for EM's, buy the others for one offs.
Best rattle can paint from my experience:
Ironlak
Montana
Rustoleum 2x
Best Stencils:
My own (reuseable, softer lines)
Pinball Pimp (excellent alignment, reproduction of the color traps)
Pinball Pal (reusable a few times, but no longer available)
I used to pull stencils as soon as I was done spraying but now I just let them sit for 24 hours and then pull. You don't have the stress of sagging vinyl or the risk of broken/stringy paint. Also the temperature/humidity in which you paint in plays a big role in how the paint will dry.
Don't try to get full coverage in one pass when the stencils are applied. Light mist coats until you just have enough paint to not see the base coat underneath is how they did it at the factory. It will also help you reduce/eliminate that raised look along the edges so many games that get restenciled have.
If you have to paint Yellow over a darker color, lightly spray the section with white first so you don't have to spray the yellow so thick.
Try to use all of the same brand for all colors and primers. This helps eliminate some weird issues you will see when paints of different brands have bad reactions with each other.
Prep is key and the longest part of the process by far. Relax and enjoy the process, these games are gorgeous when painted properly back to their previous glory.