As I know that SEO techniques have 2 parts, that are:
1. On page SEO
2. Off page SEO
With Off page SEO, we have many ways to do, and here i know some ways as listed below
1. Forum Post.
2. Directory Submission.
3. Article submission (Articles needs to provide)
4. Web 2.0 (Articles needs to provide)
5. Social Bookmarking
6. Search engine submit
7. Blog Comment
8. Ping
9. Wiki links
10. Guest Posting
11. Classified Posting etc
On-Page Search Engine Optimisation
1. Page Titles
2. Meta Descriptions
3. Meta Tags
4. URL Structure
5. Body Tags (H1, H2, H3, H4, etc.)
6. Keyword Density
7. Image SEO
8. Internal Linking
I hope this helps.