Any successful SEO plan should include a solid link exchange tactic. The more websites that link to your sites, the better ranking Google will give you.
An important factor is the link text or “anchor text” that other sites use. The text should be relevant to the keyword you are targetting.
Here is an example
WRONG
Click here to [...]

Did you know that Google ranks http://www.site.com differently to http://site.com? Anoying huh. People could be linking to your site using either link which could screw up your chances of a good PageRank.
If you’re using Apache, you can throw the below code in your website’s .htaccess file and have everything from www.site.com redirected to http://site.com - [...]