1. Keywords tag:
2. Keyword density:
Keyword density is the percentage of times a keyword or phrase appears on a web page compared to the total number of words on the page. Historically, you wanted to have your keywords be between 4 & 7% of the total words on the page.
3. Exact match domains:
This is a fairly new change (September 29, 2012). Prior to this update, Google would give a ranking boost to sites that had a domain name that exactly matched a searcher’s query.
4. Buying links:
This has always been a bad idea, but it worked until the Google Penguin update. Links are supposed to be a vote for content from one web page to another.
5. Content spinning:
Another SEO practice that has always been a bad idea, usually only practiced by fringe “black hat” SEOs. With content spinning, a marketer would take an article, run the keywords through a thesaurus or spinning tool, and republish a “spun” article with the new words. It was possible to publish hundreds or even thousands of versions of an article that were different enough that they weren’t considered duplicates.