 Re: the 5 best tips for marketing a t-shirt website
1. Be Unique. Do something different. Have an angle.
2. Know your market.
3. Advertise in front of your market in many ways (search engines, offline ads, banners, newsletters, links, word of mouth, flyers, press releases, sponsorships, giveaways. be creative)
4. Make sure your site is both search engine and people friendly.
5. Never stop finding new ways to market your products and get people seeing your stuff. As cliche as it sounds, think outside the box.
As I've always said, the best designs in the world will sit on the shelf if you don't bring the (right) customers in to see them. | 
