Develop an application that serves a need that can be fulfilled online. Once done, attack social media with a vengeance. Depending on the makeup of your social media following, a Tweet or Post to that network is like sending out 100's if not 1000's of link requests. The links tend to come naturally, you don't have to ask for them. :)
Stay way from any bulk link opportunities. ALL of them will produce less than satisfactory results and are more than likely to get you algorithmically penalized.