Personal - T-Shirt Design

I've started designing T-Shirts for the website Redbubble, a site where you can upload your designs and people can buy them, with the artist getting most of the profit per shirt.
I've only just begun, but I have one design so far:

My first T-Shirt design, based on the Mass Effect games.

I'm thinking this could be good work experience and a way to earn some money from my design work.
If you want to see the shirt on the Redbubble site, the link is below:
http://www.redbubble.com/people/djallen/works/11152569-quarian-at-heart-paragon