One thing that always works for most of us is Promotional advertising. Even though customized t-shirts are promotional advertising, I found two or three things that work well.
One is getting suckers/lollipops with your logo or picture on it and pass them out at trade shows. The website I found them at is,
www.edibledesignsbyginn.com and the customers love them. I use them as favors too.
A good friend of mine bought several empty paint cans and filled them with jelly beans, printed up labels with his information and gave them to the managers, and buyers of a local grocery food chain. By the way, they also sell t-shirts there. Anyways, he's a painter, and only gave out 25 cans, and he had his best year ever. After hearing this idea I went looking for the suckers to put my logo on, and also found that I can sell them to my customers too.
Hope this helps,