One thing that comes in handy when designing shirts for Shirt.Woot or Shirt Fight or any number of the shirt competition sites is having good blank T-shirt templates to display your design on.
A good T-shirt template will give you a really good feel of what your design might actually look like on cotton and seeing it on a shirt helps frame and position a design, and usually gives you ideas on how to improve it or what direction to take it.
My name is Kris Robinson, this is where I blog about art, computers, illustration, design, work, life and other stuff... basically anything that pops into my head.