The size of the site, and the decision keywords positioning.
Key words in the distribution of the site.
Keyword expansion of the mining and utilization.
Home page, directory page, page title tag is writing norms.
Description Tag - Description Tag, keywords Tag, ALT - instead of attributes are reasonable use.
Keyword density and keywords in the position of the web site.
Key words of type and particularity.
Whether there are keywords stack, hidden text links and cheating.