Content and structure of site
- Age of site
- Length of the domain has been registered
- Age of content
- Uniqueness of content (individuality)
- Regular updating of contents.
Relationship of sites with other sites.
- Incoming backlinks and anchor text of incoming back links
- Negative scoring for some incoming back links (from low value pages,reciprocated back links,paid links,link farm)
- Rate of acquisition of back links :Too many,too fast could indicate "unnatural "link buying activity.
- Test surrounding outward links and incoming back links
- Use of sub-domain,use of keywords in sub domains and also for well ranking stay away from only pages,frames,flash and java script.
- Stay away form link farms and paid links
- Web promotion - blogs,content sites,articles,directories,etc..
- Don't ever quit gaining quality links.