SEO, SEO, SEO. Period. I don't advertise for my store, I get 100% of my sales through google and I don't pay a dime for it. It's really the only effective way for a new boutique to advertise.
Do NOT waste your money on
banner advertisements, unless you're Mod Cloth or Shop Nasty Gal and have tens of thousands of dollars to spend every month on an extensive campaigns for simply name recognition -- because that's all it really gives you. I don't care how popular the site or or blog is, how fashion centric it is. Trust me, I learned this the hard way
Email blasts through sites like SheFinds (I think that's who I used) are a bit better, it was the only form of paid advertising that brought in any sales for me, but I still wouldn't recoup the costs and it usually only works at all if you're giving really good discounts on merchandise.
Now
web page links and sponsored posts on blogs and shopping/fashion type sites like StyleBakery are a little bit better, because they're archived and even if you don't get steady sales from them (which you probably won't) they still increase your back links from authority sites, which is an important SEO component.
I've dabbled w/
PPC, facebook ads and paid shopping sites too -- they're much more targeted but I don't think I had much luck at all with them. It was hard for me to track though. I know IM's who make bank at PPC though. If you're a beginner, and especially if you don't understand the complexities of keyword analyzation and haven't done extensive keyword research, don't bother.
But do bother to analyze and research your (niche) keywords.
Contests are pretty worthless too. Especially those who CHARGE you to run a contest. I did one once and it sounded great on paper -- in order to enter, all the users had to come to my site and pick out an item they wanted. Didn't see a single sale from it though. A free giveaway on a bigger blog might be worth it for the backlinks.
PR is good, and you don't need a PR agency to do it (although it helps x 1million). Email blogs and fashion sites and smaller fashion magazines to try and get interviews with them or to get them to post about your sales or special products. This helped me with some of my smaller lines when I first started, but after I stopped it I ended up having to drop some of those lines. Maybe try to work something out with a fashion blogger.
And like I mentioned before, SEO is the way to go -- it's the online version of "location, location, location" imo. All of my sales come from search engines. You need internal and external SEO. You can hire someone to do it, but it's really expensive. Learn to do it yourself or hire someone to do the internal and do external on your own, since it needs to be updated regularly.
Post your own content on free article websites like ezine articles (this is HUGE for sales + SEO). Write your articles about specific products and link back to them at the end of the articles -- use the keywords in your titles and as your link anchor text.
Exchange links with fashion sites, put your site in directories, use social bookmarking.
Don't forget about
social networking, it really works. And your own blog is important too -- put it on it's own domain for extra backlinks. You should have a blog, twitter and facebook FAN page -- use plug ins to connect them all so they all update each other and you don't have to spend so much time updating them individually.
/tl;dr, don't pay for anything.