A few things that could cause an over optimization penalty?

I read a good article that explains a few things that could cause an over optimization penalty, the following are the summary of the article.

Know what can cause an over optimization penalty to your site webmasterworld.com/google/4442234… #SEO
— Danang Probo Sayekti (@danpros) April 22, 2012

What could cause an over optimization penalty:

• Keyword stuffing
• Redirect several domains to one site
• Same / similar anchor in backlinks
• Same Niche same server
• Doorway / thin affiliate
• Link schemes / cheap backlink packages