One thing I do to promote my main startup is to monitor Twitter for people mentioning my competitors. For instance: An (outdated) app I’m competing with is Norton Commander. When someone mentions “Norton Commander” on Twitter, I reply to them along the lines of “Hey, if you like NC, then you might also like my app”. This brings me new - highly targetted - leads.
The following is an attempt at productizing this approach: https://poachr.herrmann.io/
It’s just the landing page for now. What do you think? Would you pay for such a service to promote your own products?