Can anyone suggest me, what are the top techniques to get Backlinks via SEO activities?

Backlink is a most important thing to get high ranking and more traffic. When you get back link from your relative sites with high PR then it is more beneficial for your website because it will increase both Rank and PR. You can get more and quality back link by following SEO activities.
•   Forum posting on high PR and relevance forum
•   Blog commenting on high pr sites
•   Article submission with unique content etc.

Content are naturally more shareable than others. For example, infographics, in-depth tutorials, embeddable images and widgets, research reports, videos, and ebooks are all easily shareable. People like visual stimuli, so images are important to give your blog content a chance to be shared and linked to again and again.

Niche Directory submission, blog commenting, forum posting, social bookmarking and classified posting are some effective strategies to get Backlinks for a site.

There are so many powerful techniques are existing which are really excellent to get backlink to site. As some of trendy options are mentioned below.

-  Forum Posting
-  Blog Commenting
-  Social Bookmarking
-  Press Release
-  Article Submission
-  PDF Submission
-  Video Submission
-  PPT Submission
-  Directory Submission
-  Profile Creation