At first I started using tissues, but I have found that cotton balls work even better. I tear apart the cotton ball to fit into the canopy, exhaust, wheel wells, etc..... and it works really well. I have also found that liquid mask is another great way of doing it. At first I was scared to try it on uneven surfaces, but if you spread it on thick with a small paint brush and let it dry for a few hours before painting it will work great. I then let my paint dry for at least 24 hours and then peel off the liquid mask. This stuff is the best invention to modlers I have found yet. It does not leave a residue and will not peel off your paint. I recently built the 1/48 scale B-58 Hustler with the bare metal paint scheme, and for those of you that know, masking tape will peel your aluminim paint right off the plastic
! Through many trial and errors, with the liquid mask I have become a master masker!?!