Important techniques of seo listed below:
1) KEYWORDS
2) Hot Titles
3) Visual Appeal
4) Content and Meta Descriptions

1. Targeting the wrong keywords
2. Forgetting to use title tags
3. Over doing flash
4. Link farms
5. Overdoing the keywords
6. Keyword density must stay below 5%
7. Duplicate content
8. Poor website navigation
9. Using images for headers
10. Unreliable web hosting