Air Force_Guy,
There's a ton of different ways to mask. I've used anything from regular invisible tape to notebook paper, to stencils. The best thing that I've found to be "gentle" on the paint has been a name brand invisible tape--like 3M, and not the generic brand of invisible tape, as they not only can pull the panit, but also leave the glue behind on the model.
Another thing is to let the masked paint thoroughly dry before applying anything to it.
Hope that helps out a little!
Carlos