Good ole Jack....
Let my son design his own tee and this is what he wanted. Didnt think I'd be able to get the fine lines done, but it worked :) Make sure your craft knife has a sharp blade in it :) Sorry for the lack of images...
Find an image and font you want, print it out or trace it off the screen.
Trace image onto contact paper/duraseal and cut out a stencil using your craft knife.
Peel backing off duraseal and stick onto tee wherever you want it. Place cardboard in the tee so paint doesnt bleed through to the back.
Using your sponge brush n fabric paint, dab dab dab the paint in the stencil. Dry using the hair dryer.
Apply another coat and dry, check if you've missed any spots, if you have, do another coat and dry.
Turn your tee inside out and hook onto the end of your ironing board. Iron directly on the back of the print, watch out for fumes. Iron for 1-2 minutes.
Turn in the right way and wear!! :)