Following these simple tips will definitely boost your traffic and search engine rankings for free.
1. Make sure your site is not under construction, incomplete, with little or no unique content.
2. When your site is ready, submit it to Google, Yahoo, MSN and ASK.com. Consider also submitting to other search engine but most of them are powered by these four leading search engines. Submit also your site to reputable high PR web directories, open directories, yellow pages and social bookmarking sites such as del.icio.us, furl, etc.
3. Submit your sitemap to Google, Yahoo, MSN and ASK.com (sitemap for search engines usually in XML format)
4. Offer sitemap to your site visitors for easy page navigation. (sitemap for visitors in HTML format)
5. Create unique and rich content sites. Avoid duplicate content. Do not create multiple pages, sub-domains, domains, mirror sites or sites with different domain names but same content.
6. Check your keywords and make sure they are relevant and actually are contained in your site. Avoid keywords stuffing.
7. Use text instead of images in your content, links and important subjects.
8. Make your TITLE and ALT tags descriptive, simple and keyword rich. Avoid irrelevant and repeated keywords.
9. Title tag should be 60-80 characters maximum length.
10. Meta tag description should be 160-180 characters including spaces. (about 25-30 words)
11. Meta Tag keywords must be 15-20 words maximum.
12. Optimize Pages with Headings (H1, H2, H3..) containing your site's primary keywords.
13. Validate your CSS and HTML. Check for errors and broken links.
14. If your site contains dynamic pages(i.e., the URL contains a "?" character), make sure you use SEO friendly URLs. Search engines' spiders having difficulty indexing dynamic pages.
15. Maximum links per page must be fewer than 100. Avoid the risk of being flagged as link farm by search engines.
16. Use Lynx as text browser to check your site. (http://lynx.isc.org/)
17. Allow search bots (good ones) to crawl your sites without session IDs or arguments that track their path through the site. Using these techniques may result in incomplete indexing of your site.
18. Check your web server/host if it supports the If-Modified-Since HTTP header. It tells search engines whether your content has changed since last crawled your site. It will save you bandwidth, resources and avoid server overload.
19. Use Robots.txt file to manage and control search engine spiders in indexing your site. You can allow and disallow spiders and choose directories you want to be crawled and indexed. But with bad bots or spam bots you need to modify your HTACCESS file to properly and effectively manage bots or spiders. Visit http://www.robotstxt.org/wc/faq.html to learn more about Robots.txt file.
20. Do not attempt to present different content to search engines than what you show to your site visitors.
21. Avoid dirty tricks and exploiting loop holes to improve search engines ranking.
22. Avoid links to bad neighborhood such as web spammers, link farms, phishing, hacker, crack, gambling, porn and scam sites. Linking to them will greatly affects your search engine rankings.
23. Do not attempt to join in link schemes, excessive reciprocal links or excessive link exchanging and link exchange web rings.
24. Do not use unauthorized programs or online tools to submit your site, check page rankings and other automated queries. Avoid the risk of being flagged as spam.
25. Do not use hidden text and links. Show to search engines what you show to your vistors. It will greatly affect your site's reputation.
26. Do not attempt to create pages that contains phishing, scam, viruses, trojans, backdoors, spyware, adware and other malicious programs.
27. Make your site useful and informative.
28. Improve your link building. Link to high PR websites. Quality of relevant links are far more important than quantity. Links will greatly improve your site's visibility, popularity and rankings. Search engines consider links as votes to your site.
29. Check your page link structure. Every page should be reachable by a single static text link.
30. Be extra careful in purchasing SEO services. Some uses illegal and questionable ways to improve rankings.
31. Do not buy or sell links.
32. Do not create sites that contains purely affiliate links and no valuable content that are useful to the users.
I hope these tips will add more popularity and visibility to your site. Enjoy!