SEO - what's best for search engine optimization?

[Jorge S]

I run my own site, don't have lots of money to hire a SEO company to do my site optimization, I have done relevant links and worked on meta tags, etc... However Google is taking a long time to catch my incoming links, I ranked #7 on Yahoo for a very competitive keyword, MSN somewhere on the second page, I added an RSS page to distribute some articles I wrote and also added a XML site map that I submitted to Google.
What else can I do to boost my search engine ranking?
My site is about 4 years old and at one point I stopped acquiring incoming links and not too long ago I started getting more links. I am so exhausted and loose sleep over this, what can I do?
Comments are much appreciated.
Thanks in advanced!
Thanks for your comments, I did mention that I have some articles and content is not a problem on my site. Besides having plenty of content I also have the rss feeds pointing to my home page, however I control the articles that I want to publish on my home page (usually I publish articles that are relevant to my site).