What do you need to know about your target audience?
What are their interests? Do some research and see if there are any typical or general interests the target audience has. If you already know them or know their interests, then you are ahead of the game. Of course, since you are the expert in your niche, or should be, you will know a lot about their interests already.
You can do some research on social media to find out what their interests are as well. Facebook has groups and so does twitter. Find a group related to your niche and observe it to see what people are talking about. Use this as advice on what types of products or services to market as well.
The best advice for using social media groups to learn more about your target audience is not to join any group and post on there asking all kinds of questions. For instance, you don’t want to join a group and then ask everyone to give their opinion about their favorite game, or gadget. Just observe first, and then engage in the conversation as you would with a friend. Get to know people first, and then ask them questions here and there. It is all about patience.