What are some tools and tips for designing t-shirt prints?

I am going to try it soon... I will be using Adobe Illustrator for designing the prints, the size of the print should be as large as it is possible I guess. Also, as for the blank tees, I am going to try some of those from www.gotapparel.com/c-1-t-shirts.aspx for example. Have you ever bought the stuff from there? Maybe you will find that store helpful to you too...