How do I use gel medium to affix emblems on figures?

This is known as decoupage, and there are a number of ways to go about this. (There are also many other customizers out there who are higher authorities on this subject.) In general, you’ll want to apply some of the gel medium to the back of the paper emblem, and some to the target area of the figure. Apply the emblem, and then use the brush to smooth out the excess gel medium along the edges. You can even brush the gel medium over the emblem, so as to seal it. This action along the edges also helps to smooth out the “seam” of the emblem, allowing it to appear as though it were printed directly on the figure. One warning: Don’t smear too much if your emblems were made on an ink-jet printer. I’ve smeared many a super-hero symbol this way. (Laser printed emblems won’t smear.) If you do use ink-jet printed emblems, try spraying them with Testor’s Dull Cote or some other fixative before applying to the figure with matte gel. That will cut down on the smearing.