You can buy links on the similar websites or some great fashion blogs... and also do some article submission and directory submission of your website and also if you budget is stretchable so... try adwords...
actually, a lot of people are asking almost the same question frequently but by using different site as the subject. for your information, any site can be promote in either of those methods; -by using ppc program such as adwords, bidvertiser or maybe beskot for the free one. - forum - seo technique - banner - affiliate - etc.
For faster results, try PPC advertising like adwords. You can also go to forums where lots of people would be interested in buying your products and advertise there, but don't spam.
Seo / Advertising => invest money or do it yourself if you have the skills (seo i refer) advertising costs anyway
If you're selling products try PPC marketing with programs such as Google Adwords. Tip: It's more effective to link your ad directly to the product/item page rather than the homepage.
for ecommerce use PPC it is the best and most easiest - or social networks. the only thing ecommerce does not work well is with seo - since all pages are static and never updates and have poor content. so it is best to pay for traffic that you can get results fast - ppc is the way to go use targeted keywords and pay less for those keywords.
You should try using the social shopping, it is a method of e-commerce site on which users can communicate information about products, services and a deals. It can generate revenue not only from advertising and click, but also by sharing information about their users with retailers.
maybe pay some people to put out posters near fashion stores advertising your site (although the store employee's would take it down, maybe try and get permission to put them up)