One of the most important factors in getting your pages ranked higher in the search engines is the number and quality of incoming links.
The value of links to your page is related to the PageRank of the page that links to your page. The higher the PageRank, the higher the value. However, the increase in value isn’t in a straight line… It seems that each level is about 10 times more valuable than the level below it.
So focus on getting quality links, rather than quantity. Or better still, if you can, focus on quality AND quantity.
Even if you know nothing about on-page search engine optimization, your site can still rank quite well just by having enough quality incoming links.
Lots of quality incoming links can even compensate for not having the keyword on the page. What do I mean? Usually, if you want a page to rank for red widgets you need to have red widgets mentioned somewhere on the page. But with enough links, you can rank #1 for something that doesn’t appear on the page… even if there are millions of sites in the search engine index for that term. Just google “click here” and look at the top results if you don’t believe me :)
To sum up, if you’re not ranking well for a particular keyword, your first step should be to get more links to your site. Don’t worry about anything else until you have that fixed.