What I usually do is wait until after Ive painted the bait, then I shoot regular rattlecan enamel or laquer clear over the whole bait. This seals the paint job as well as makes the bill or lip clear.
This is just me, but if I am doing a repaint, I'll typically only sand the existing paint down enough to ensure good paint adhesion. Then I'll put my "priming" basecoat on and go from there.
You can get a woodburner with a stencil cutting tip at most walmarts for around 10 bucks or so. I wouldn't do it in the living room, but they do a pretty good job since you are melting your way through instead of cutting. Hope this helps