How long do visitors spend on your website currently?
First, try to double that in the next 30 days and then try tripliing it. So, if visitors to your site are currently spending one minute there, the goal is to get them to spend two minutes and then increase it from there.
The next thing to consider is your search keywords. What terms are visitors typing into the search engines to find your site? Do these keywords jive with your offerings? If not, people will visit the site and then exit quickly -- so make sure the content they find on the site is the content they're looking for.
Lastly, websites that get a lot of long-term, long-staying visitors have compelling, fresh content. Do you? If not, how can you add fresh, new, exciting content to your website at least three times a week? Staring a blog could be a great idea.