Moz is one of my favorite sites. I have the paid version and in-depth resources like this in the free version are what sold me. It goes beyond tactics into strategy, which is important if you want to maximize your exposure. In my opinion, this is a guide you should fully review before you pay for in-depth knowledge from any other source.
When you're ready to truly understand how to use social media for exposure, communication, PR, personal use and how it fits into the larger context of digital life, this is what to read.