Originally Posted by scottspfd82
Talk to 100 people in your demographic. Ask if they'd even wear the shirts, much less buy them. If you get an overwhelming "fuck yeah" type of response, then proceed to roll out.
Shirts are a market that you'll be able to tell pretty quickly, if they don't sell themselves from the start you're most likely wasting any money on marketing them.
After you've followed through with this, proceed to find sites/forums that you can post on with an audience that would be interested in your shirts.
Contribute, and try to seem like a nice person.
In your signature, have some apologetic/help me out pitch like this:
"Hey guys, I'm entering the ___ shirt scene! I put a lot of effort into these, check em out!"
This is a very friendly way of making it go somewhat viral to your audience, since you're leaving your mark at where ever you post and the forum members will more than likely spread the word if your shirts are great.