A balanced approach is best for website promotion. The most successful sites tend to include the following elements:
1. Fresh, Unique and Relevant content. Add to this daily if possible.
2. Proper site set up to ensure easy and intuitive navigation.
3. Sitemap in xml and html
4. Proper Meta and body tags.
5. No hidden text on page or anything that appears spammy to search engines.
6. Obtain incoming links from related sites. If possible gather links from authority sites even if you must pay.
7. Dynamic content including news, blog and forums.
8. Integrate with all major social networks and have links for user to bookmark or rate you on each page.
http://www.sharethis.com offers a great free button that you can configure and add to your site to simplify process.
10. Write weekly articles for distribution via Free Content directories. Make sure your author box is set up properly to provide you with backlinks to your main site(s)
11. Add a signature at all the message boards and blogs that you frequent and chat on.
12. Dont buy links from bad neighborhoods. This includes banner farms, ****** "$100 for 10,000 links deals", adult sites etc...
13. Add incoming links slowly and vary the anchor text. Adding too many links too quickly sends up a red flag to search engines.
14. Obtain Links to sub pages within your site.
15. Be patient and consistent. It takes months to get established at most search engines so focus on the above tips and the rankings will come.