I have seen lot of newbie webmasters doing some aggresive SEO for their sites which can infact lead to banning of their site by search engines. SEO (Search Engine Optimization) needs to studied well and according to latest search engine guidelines.

Some of the Dont’s for SEO :

Dont use blackhat techniques
Dont link on bad neighbourhood
Dont do aggressive link building
Dont use link farms
Dont stuff your content with keywords/footer words aggresively
Dont use duplicate content OR article marketing with same content everywhere

Some of the Best tips you should keep in mind :

Content is the king. Keep the keyword limit to 3-5%
Use different anchors for link building
Do link building slowly
Do link building from related niche sites
Meta-tags are still important
SEO friendly url structure
Use title tag and alt tag for links and images (google images is a good source of traffic too)
valid Html/PHP/CSS coding
Use robots.txt and sitemap files

These are some of the Do’s and Don’t you need to follow for doing SEO for your site. If you can’t, hire some reliable seo services.