I've never sprayed over a stencil before, but I really wanted a Beast Wars (Transformers) shirt. My favorite characters are Black Arachnia and Silverbolt, so naturally one of them seemed like a good place to start.
I'm sure there are easier ways, but this is how I went about it:
I went to a silkscreening shop on the boardwalk and picked up a nice, plain black shirt.
I printed out the Predacon symbol fitted to an 8 x 10 piece of paper.
Exacto-knifed out the design, traced it onto a cardboard shoebox lid.
Exacto-knifed that out (Didn't have a handle for the blade. Sheesh. Took forever.)
Set the shirt with the cardboard shirt thing inside it, set the stencil, spray painted gold fabric paint.
Used a lolipop stick to fill in the lines for holding the gaps in place.
I'm incredibly proud of it. I'm thinking of doing the Maximal sign in gold on a silver shirt next (or some comination of blue/silver/gold) for Silverbolt.