What more should I do to increase my site's SEO and Google rankings?

[Ivor]

EzineArticles are no.1 so you may as well start there. The link will be followed by Google also when more publishers link to your article the PR will increase. There are other sites some are "nofollow" which is not much good to you.
If you are lucky you might get some free back links when articles are published, but does not always happen. Write to the highest standard and make sure they are related to your niche using your keywords but not commercial.
You will still need to bookmark on social sites to maximise traffic ie Facebook, Stumbleupon and others.
Ensure you have good articles on your website to keep your new visitors and use good links to other parts of your site, if you create lots of new web pages, they will be indexed faster.
Make page titles keyword rich and not to short or too long, about 5 words.