I see your designs look great on the t-shirts, too. I upload my designs in PNG format, at twice the size that Zazzle recommends; for example, instead of making the design 12x14 inches (1800x2100 pixels) at 150 ppi, I make it 24x28 inches (7200x8400 pixels) at 300 ppi. And, of course, I place the design where it'll look best on the t-shirt, which is normally centered (widthwise) and on top (lengthwise). BTW, the latest changes in Zazzle's format are awesome! Keeps getting better! What do you think?