Hey Ashok! Good question. I work with clients in a lot of different industries, so the tactics I employ are often quite different depending on the client. In general though, creating killer resources around popular topics, or tools related to client services. This provides a ton of outreach opportunity. For example: We had a client build a tool that allowed webmasters to quickly run SSL scans on their sites and identofy non-secure resources. We reached out to people writing about SSLs, Https migration etc and pitched it as a value-add. We built ~50 links to that tool in 45 days. Not a massive total, but they were pretty much all DR 40+.
This community is full of opportunities if you're a fashion-based retailer. One of the major advantages is the fact that they add links to each of the products that they feature within their outfits - the links go directly to product pages. This is the holy grail for ecommerce SEO, and the traffic those links will bring through will convert at a very high rate.
On April 24, 2012 many started to see that Google has started to penalize companies that are buying links for the purpose of passing off the rank. The Google Update was called Penguin. Since then, there have been several different Penguin/Panda updates rolled out by Google. SEM has, however, nothing to do with link buying and focuses on organic SEO and PPC management. As of October 20, 2014 Google has released three official revisions of their Penguin Update.
Although it may have changed slightly since BrightEdge published its report last year, the data still seem to hold true. Organic is simply better for delivering relevant traffic. The only channel that performs better in some capacities is paid search ads, but that is only for conversions, not overall traffic delivery (Paid Search only accounted for 10 percent of overall total traffic).