Depending on the level of detail you might also check out Scotch Fine Line automotive masking tape, used by body shops to do some of their more detailed pinstripe work and so forth. It comes as small as 3/32" in width, has an extremely clean masking edge and releases nicely. Since I do N-scale it especially comes in handy all the time, but I can imagine that some HO or larger paint jobs might have areas of detail where that would come in handy.