I Will Start With Profile Backlink.

  What are profile links: These are links you build when you register on any site that allow you to add your site to the profile page
For Example: We All Known Top Forum In Nigeria, I mean NAIRALAND, If You have account there or You Can Go and Create,
After You Done With Your Registration, When you edit your profile  add your link as the signature page (automatically you have gotten a profile link and google will count that as backlink) quality one for that matter
The issue now is : How can i find the websites that enable me register and add my links to profile page?
Yes that's also a challenge but with good research and hardwork you will always make it out.

You Can Just Visit Google and Search For
Keyword: List Of Do Follow Profile Backlink
Profile Backlink Site
High DA Profile Backlink List

That how You Can Get Your Backlink also I Will Share Some Links Below For You To Start Your Link Building.

http://www.last.fm https://soundcloud.com https://africoders.com https://zegist.com https://app.net/ https://everyknows.com https://www.asknaij.com https://visual.ly/ https://getsatisfaction.com https://about.me https://steepster.com http://www.myvidster.com https://angel.co/ https://ello.co https://www.arduino.cc/ https://stocktwits.com/ https://trendguy.bigcartel.com https://bigcartel.com https://www.chordie.com/forum/ https://bestnaija.com https://allihoopa.com https://webflow.com http://www.authorstream.com freemusicarchive.org https://yourlisten.com https://www.ultimate-guitar.com/