What field is it in? For ours ( http://feefighters.com ), which is b2b app, we have a 6 pronged attack which works pretty well: 1) SEO - people find us when they search for credit card processing and lots of long tail keywords. This is a long term thing but completely worth it. Make sure all of your pages are optimized for SEO. 2) SEM - we were buying keywords on google/bing/yahoo. Facebook has been less effective fo…
Just keep experimenting. First exhaust all the tried and tested methods and then experiment