Oh, a few tips for the contest.

1. JPG files are best with the lowets compression possible.
2. JPG's support many more colours, but slightly distort the image to
compress the file size. For photos, the human eye can't tell the
difference, but along straight edges and in pictures with large solid
colours, the distortion becomes apparent.
3. For most t-shirt stuff, like logos and text, 256 colors is more than
enough, and will give you the best results. Transparent GIFs will not
work well, however.

Penned by my hand on the 11th of Lupar, in the year 284 AF.