As entrepeneurs we often make the mistake of thinking, that everyone will be as excited about our project as we are ourselves. That is not the case most often though, and you really need to see it from their angle: What is Brand X doing for me?
That basicly means you need to provide some sort of value to get fans - and to retain them.
I would focus on Facebook to start with, as you can segment it really well, and the prices are still lower than they could/should be.
Create posts related to your market, that gives your users some sort of value - interesting knowledge, lifted emotions, a laugh etc, but keep it related to your own brand/message!
Then you can push some of those posts with a small cpm or cpc budget, to see what works best for you, and from there analyse the data to see what works best for you to reach new engaging (and potential) customers, as well as gaining knowledge of what information gets dynamic thrust.