First, you need to make sure that your on-page optimization is done correctly. Make sure you're targeting the right keywords and that you have good optimized content for your keywords. Then, take a look at all of your tags (title, description, keyword, heading tags) and make sure they're optimized correctly. To see them, log onto your site, click "view", then go to "page source".
Once you've got your on-page optimization taken care of, it's time to head off site. Check the top 3 results for your keyword - how many links do they have? How many quality links to do they have? How long have they been online? How high is their PR
? You can't do anything about PR
and age of domain - but you don't necessarily need a higher PR
or an older website to beat them. (now, if the top site has been around for 15 years and has a PR
of 8, that may be another story...)
See what links they have, and try to get the same ones. For example, if they have a link to XYZ Directory, go to XYZ directory and see if you can get a link from there, too. If they have links from ABC forum, head over there and start posting.
Do not resort to paying for links from link farms. Google will find out what you're up to, and they will not be happy.
At the same time, keep building your own quality links - through article marketing, guest blogging, forum posting, social bookmarking, etc.
It may take some time and alot of hard work, but, hopefully, it will all pay off! Good luck!