What are the various techniques of Link Building?

Outreach. Most every good link building tactic revolves around outreach. ...
Guest blogging... with a twist. ...
Broken link building. ...
Unlinked mentions. ...
Link reclamation. ...
Paid promotion for "linkable assets" ...
Steal links from inferior web pages. ...
Content repurposing & syndication.

Following are some of the best link building technique

-Forum posting
-Social Bookmarking
-Web 2.0
-Article submission
-Guest Post
-Document submission
-Blog commenting

Social Bookmarking,
Web 2.0,
Forums,
PDF submissions,
Press Releases
Directory

Guest posting
Article submission
Press release submission
Social bookmarks
Classified ads
Infographics submission