On average, 10% of our early users became online daters on our site, and the other 90% were spreading the word in one way or another, but we never heard from them again.
As we got bigger, we slowly shifted our message towards the dating side of things, as those "growth hacks" diluted our message. Consider (1) Tinder, a very simple dating app, which has become a phenomenon.
Heck, you could throw key parties (pun intended) where people could swap their credentials!
Or instead of a traditional dating-app, make a geisha-app. Just throwing random ideas out there, but the general idea is either you cater to a niche, or you better have a massive marketing budget to take on the OKCupids of this world.
Me and a friend are going to be developing a dating app for some fun.
The development will be difficult but we feel that getting people to actually use it will be even harder.
But we made it easier at the beginning for users to introduce their own questions.