In SEO be sure to get the right keyword density. Use keywords evenly throughout your title, headers, and your articles, as well as in other areas on the page that will call your article to the attention of search engines. one to two percent keyword density is considered best these days. That means one or two keywords per 100 words is optimum.
When creating backlinks to your website in order to increase your web site's search engine ranking, remember which factors determine the value of a link. A quality backlink depends on the anchor text in the link, the pagerank of the page linking to your website, the page title of the page linking to your website, the reputation and quality of the website linking to your website and the method used to create the backlink.
Use new domains instead of creating sub-domains if you want to raise your search engine rankings. Sub-domains confuse your human users, as they may not understand the difference between subdomain.mainsite.com and mainsite.com, and these may be very different pages. Search engines spiders will treat sub-domains as part of the same site, diluting the power of your keywords and your site theme. It is better to move such content to its own domain instead.