While content is king in the world of web sites, it is useless without exposure. If you create enough content you will eventually rank for some long tail keywords, but you can increase your traffic dramatically by doing a little external SEO after you post an article.
Obviously, you should have SEO in mind when writing your articles by including keyword rich titles and have your targeted keywords in mind when writing but aside from that Google will rank your article much higher if you have a few backlinks pointing to the article from credible sources.
The first step after publishing a piece of content should be some immediate link building. Obviously if your content is good enough, other webmasters will naturally link to you, but getting the ball rolling on your own will never hurt. Not only does building a few backlinks to your article improve your chances of placing high in Google, but it also increases the rate at which you are indexed. Some methods to build backlinks are social bookmarking (digg.com, Mixx.com, etc), article promotion, and posting your links on forums you frequent (Make sure do NOT spam).
The bottom line is, if you are spending 30 minutes to an hour writing a piece of content, take an extra ten minutes afterwards building a few solid back links to it and you should see much greater results.