The following SEO tactics are considered black hat and should not be exercised at all if you want to stay above board with Google and other search engines:
1. Content Automation
2. Doorway Pages
3. Hidden Text or Links
4. Keyword Stuffing
5. Reporting a Competitor (or Negative SEO)
6. Sneaky Redirects
7. Cloaking
8. Link Schemes
9. Guest Posting Networks
10. Link Manipulation (including buying links)
11. Article Spinning
12. Link Farms, Link Wheels or Link Networks
13. Rich Snippet Markup Spam
14. Automated Queries to Google
15 .Creating pages, subdomains, or domains with duplicate content
16. Pages with malicious behavior, such as phishing, viruses, trojans, and other malware
Good luck to you,