For link building, you may use forums like reditt, or approach a bunch of PR resources or a bunch of blog websites, directories of businesses like clutch, goodfirms, yeloowpages and all those, blogs, infographics, create blogs that other people can add to as well. further, work on PR to get through resources like journalists etc. Try to get warm intros with journalists etc. pitch to about 100 each month and ask them if they want to use my specific content