Start with all the free stuff first once you get your site up and running like;
1. Make sure all your pages are
SEO
2. Email friends and get them to email there friends.
3. List on sites that will help giving your site more exposure
4. If you clothing is for females, then join a few female forums like vogue and so on.
5. Build some quality reciprical links
Other ideas that will cost a little money
1. Sell you clothes on Ebay.
2. Use something like facebook for advertising to target age groups and gender.
3. Google/Yahoo adwords are always pretty good as well
4. Affilate Programs
5. Flyers, Radio and TV
And so on. There are plenty of ways to market your business, I would just start with the free stuff first and build from there.