There may be several issues:
1.) You may target wrong keywords
2.) You are doing something wrong in link building (did you diversify your link profile, added links from high quality sources, ...)
There are also other options (your website is too slow, Google doesn't truest you, ...). If you tell more, we'll be able to give more detailed advice.
Are you willing to revenue share 50/50 with the person who sorts out your site?
some kind of contest on FB and twitter will boost your traffic
try also to build a list like that you will get repeat visitors