You need to think who your target group of users is.
Create Personas, describe them. How old are they? How much do they earn? Where do they live? Married, kids, divorced, widowed, suicidal etc.?
Once you defined your target group, you need to find the ones who influence this group (the "influencers"). Find 10 of them and engage them socially.
That means different things. Follow them on social networks and engage them in meaningful conversation. Cold-email them with your pitch. Ask them out. Write a guest blog post. Be honest about your intentions.