I read all kinds of stenciling tutorials, but I don't have freezer paper or anything else, and I really wanted a stenciled t-shirt.
So I found the image on-line, printed it, took my carbon paper, placed it on the t-shirt under the printed image and then traced the outline of the stencil (this works best on a light color).
I then took my black fabric marker and simply filled in the stencil. No messy paint, no arranging the stencil to make it just right, simple and easy.