This question is just too broad for a specific useful answer. So I'll try to be more generically helpful...
You have been engaging with the people whose problem you solve? If not, you are doing it wrong and need to get current on lean startup and other modern approaches to building a startup. They can basically be summarized by: Sell it before you build it!
If you are closely engaged with your target customers, or at least the early adopters who have the problem you address so acutely that they will give an unproven startup a try, then you already know what your target market looks like and have your beta PAYING customers all ready to go. From here, you examine where people with this same problem hang out in the world and you go to those places and keep refining your story, product, and techniques -- all the while gaining customers and credibility.
At the end of the day, there are NO magic formula or approaches. You need to find the unique blend that works for you in your situation and that takes hard work and some luck.