My introduction to social media

I am an avid Facebook user and have always been a little intimidated by the other social mediums (is that the right use of the word?) that I know other people use.  Words like Twitter and HootSuite and Instagram always come up and I am aware they exist, but I don’t know what place those things have in my life.  Everyone I know is on Facebook, and so far it’s treated me pretty well.  But I don’t really understand the choices people make to decide between using Facebook, Twitter, Instagram, etc.  I know those sites exist, and I understand they all must have some unique value, but I don’t yet understand what those values are, or how they all fit together to be relevant in my life.
When I was coming up with my New Years resolutions for this year, it seemed like a cool idea to focus some attention on the parts of the Internet I know less about, and maybe try and see where I might be able to draw inspiration in my life.  So I decided to create accounts with all the major social media sites, and try to start posting to them and using them on a regular basis.  My goal is to decide where the value lies in each site, and figure out how they all fit together in the bigger picture of social media.

To start, I created accounts on these sites:

• Twitter
• Instagram
• Pinterest
• Vine (from Twitter, a site for 6-second video clips)

Creating the accounts was just the first step, next I have to figure out what voice I want to have on each.  I am hoping that time will give clarity to some of the things I don’t yet understand.  And I’d love to hear ideas for other sites to try!  I should really include Blogspot in my posts, but I’m really just getting started with this blog and I don’t think anybody is reading it yet, so I don’t think I’ve quite grasped the concept yet.

Are there any other sites I should focus on?