Lessons learnt the hardway...
If your business relies on SEO to get customers or users or as primary driver for revenue, you are in for trouble. Just a simple algo change by Goog or Bing can put you out of business. (There have been numerous instances of this happening).
Your business is at the mercy of G&B once you rely on SEO.
If you are starting to build backlinks to your website, consider this: (a) is this going to be of value add to your users or (b) is it solely for G&B to increase your search rank. If the latter, then all you are doing is polluting the internet with useless links for machines to crawl.
Direct visits to your website as most importantsource of traffic (don't have to rely on 3rd party like G&B)
App installs; once your app gets on your customer's phone, you can keep updating it, sending notifications etc. (still a minor risk, since relying on 3rd party app stores)
Have your user signup and provide value add for signing up & logging in. This will decouple your traffic from G&B.
Reach out to users directly and have them sign-up (relevant forums, mailing lists, followers etc.)