The popular SEO Techniques are
1. Forum submission
2. Article submission
3. Social Bookmarking
4. Directory Submission
5. Guest posters

SEO Off page activity is a best popular technique is, Bookmarking Article Forum Directory Listing Profile creation. PDF Submission.

The Popular SEO techniques are
1. Social Bookmarking
2. Forum Submission
3. Blog submission
4. Article Submission

.social bookmarking
.Forum posting
.QnA
.Blog commenting
.Web2.0
.Article submission
.Blogging

Great quality backlinks from High PR sites and good content of the web site are popular.

Article Sharing
Blog posting
Forum
web 2.0
Guest posting
socail bookmarking

On Page:
titles
tags
content relevance/length ratio
Off Pages:
Strong backlinks
Ads

Both techniques are important but On-page need only once but Off page required daily update and work

Bookmarking Submission
Forum Posting
Guest Blog Posting

Blog posting,
Forum submission,
Social Bookmarking submission,
Search engine submission,
Directory submission,
Article submission,
PDF submission

Some Popular SEO techniques:

1. Article submission
2. Blog commenting
3. Blog posting
4. Social bookmarking
5. Business listing
6. Slide sharing
7. Forum Postings

Top 10 popular SEO techniques.
1. Article submission
2. Blog commenting
3. Blog posting
4. Social bookmarking
5. Business listing
6. Slide sharing
7. Forum Postings
8. Image sharing
9. PDF/PPT sharing
10. Micro blogging

On-Page, Off-Page & Social Media Marketing SEO techniques are most important today