I've painted a number of cabinets mostly with stencils I have made. I've gotten better over the years. Recently, I did a Flipper Cowboy with stencils I purchased. I will NEVER buy another set of stick on stencils again. They don't allow you to have that tapered kind of fuzzy edge ...especially important on Gottliebs. Stick on stencils are very difficult to use (for me anyway) as well. I trace the design using tracing paper, then attach the traced paper on top of oil board that is the actual stencil. I then put carbon paper in the middle and retrace the design. I do this for all colors. Oil board is expensive, but it's much better than poster board that I've seen discussed. Cut out the stencil and compare it to the original cabinet if I have it.
Here are some photos of a TKO I did for a friend.
http://s710.photobucket.com/user/pinballdave/library/TKO/In%20progress%20Painting