Greg,
All your masks should be cut before applying them to your plane. The cuts in the surface are going to show. A lot of guys get masks made by designing their paint scheme using something like CorelDraw or Adobe Illustrator and getting a sign shop to make the masks using special masking vinyl. Phil Granderson make all his masks himself as does Mike Haverly. Chris Cox and I just bought a vinyl cutter for ourselves a few weeks ago. Your only other option is to get lots of rolls of tape, like 3M "Fineline", and lay out your design with it.
Alan Resinger