I'd suggest breaking down what you want to do even further and specializing in just one area. Get really good at that and offer that service. As an example: I love all social media marketing but decided to niche down to Facebook Marketing. Went even further and offer Facebook Page Makeover and Marketing.

If you don't feel as if you are really good at any of it yet, what excites you the most? Again, I like all social platforms but I live and love Facebook so I went with Facebook. I have a good knowledge of all platforms, but gravitate to Facebook most. I also love learning new strategies to use on Facebook and enjoy sharing it with others.

Hope the example helps you figure out what one area to focus on and offer your services there.