which is best link building strategy

By far the best link building method is to create your own private blog network, many will criticize this but if you look at the link profiles of some of the largest companies ranking on the first page of google most have a network boosting their rankings or have cunningly hidden it using spyderspanker etc. I personally use this technique and hold dozens of first page rankings across some of the most competitive niches out there with hundreds of thousands of searches per month.

 

Create Web 2.0 Sites
Post Comment on Niche blog/Forum
External Blog Submission
Infographic Submission
and most important Sharing on social networks with quality content and images