If you thought it was tough to build your site, website promotion will change your perspective. Think about it. There are millions of websites just within your niche that you will have to compete with. Luckily, if you have built your site well, promotion will not be as hard as you think. So how do you get people to notice your site?
Backlinks
You will need to build hundreds, or thousands, of quality backlinks to ensure that you are listed high on Google. There are tons of different sites that you can build backlinks on and here are a few approaches.
Article Marketing
This is a good long term approach. There are many different article marketing sites that you can submit to, but for now just start off with Ezine Articles. They have a huge page rank and that will trickle down to your site. Write as many articles as you are able to on Ezine Articles because your writing could become syndicated, and that will help you build even more links.
Social Bookmarking
Sites like Digg, Stumble Upon, and Delicious are all examples of good social bookmarking sites. It is debatable as to whether or not these work well, but every little bit helps. Just make sure not to spam these sites or it could hurt your efforts.
Guest Blogging
This is similar to article marketing, but you will get more direct traffic this way. Your guest blog will be submitted to the thousands of followers for that blog. You could gain some substantial repeat traffic this way.
Blog Commenting
Every day, go on Google Blog search and make a couple comments on relative blogs. It is great if these blogs are dofollow, but don't hold your breath. Make interesting comments, and you may get some traffic out of it.
This is just a start of what you can do to help promote your blog. Just make sure that you don't fall into the trap of buying any automatic link building programs. If Google gets wind of this, and Google knows all, they will blacklist your site.
I will be posting a free download of many of the different article directories on the web.