How to "Steal" twitter's & instagram's userbase?!

A project without audience is nothing, hard lesson learned from spending months on coding without marketing.

Based on that, marketing on social media platforms these days is good for acquiring a small userbase, the question is what's your strategies on social media to gain more followers and more audience for what you would want to market next.

Besides DM's that are limited to about 15 a day, posting on popular tweets, and making contests and prizes?

Also have anyone tried their ads network? What was your success?

what other strategies would you recommend? Multi accounts?