Sgt_Kickaxe - 11:32 am on Mar 4, 2012 (gmt 0)
Ease up, what suhanaanjum said is basically correct, I'll elaborate for him.
For starters you can open up Google webmaster tools and see the list of keywords Google has assigned as important to your site. You can then look up, while still in GWT, which pages Google thinks rank best for those keywords. If you agree with Google's assessment you can then make sure those pages are easy to reach from the index page(assess internal link structure) and tweak the SEO on them as best you can. You can also remove duplicate pages that aren't ranking for those keywords, or better yet improve them and have them target other keywords.
When you have a clear list of which pages best support which keywords you can begin your link building efforts for those pages/keywords. You should have had this list ready before building the site but it's better late than never.
More advanced tip - interlink articles to improve their rank a little as well as reduce the perceived importance of your category pages. When you write non-essential type articles in the future place them in a category that you do not interlink with and they will not compete against your existing pages. This also makes it easy to use robots.txt on an entire category of non-essential pages, if you want to take that route.
Incoming links are always welcome, having them lead to the right places is even better and not wasting a drop of their value is optimal. I wouldn't waste too much effort on one type of activity over another, creating great content is always your best bet with your time in the long run.