One of the things I really enjoy doing is designing apparel. It doesn't always mean creating the original artwork per se. The skill is in the process of arranging existing art and perhaps some original elements to create a strong, unique overall aesthetic. Here are some hoodies that I did a couple of years ago. The final items were somewhat close to these but some elements were ultimately left out. I learned to ask for more detail than you think you can get early in the design process. That way, you'll likely end up with more after the cost reducing commences.