Best Blackhat Forum

- Duplicating content.
- Not using analytics to know what converts.
- Bad backlinks.
- Not promoting posts.
- Ignoring image optimization.
- Not optimising on local search.
- Not using anchor text for internal links.
- Focusing on link quantity instead of link quality.
- Not having unique meta description and title tags.
- Not using available keyword tools.
Can you add anything else?

Great list, another thing I would add is, "Don't stuff keywords where they don't make sense, use them organically, you're writing for humans to, not just search engines."

Simple seo mistakes:
Lacking the Winemaster and analytic
Missing the Alt tag
Missing the favicon
Duplicate Content