I think building an on line educational community and participating in a PLN is fabulous. You will be making connections with others, sharing and receiving ideas and information with others with similar interests.
A couple of points that stood out to me about commenting were to write meaningful comments and not to be afraid. I am a lurker of blogs. I love viewing and reading what others have shared but comment rarely. I can see how making a comment can promote conversations amongst others and get wheels turning. When I do comment it's usually short and sweet, so I will be working on this as I move through this process.
Here are the blogs I am following as of right now. I am sure this list will grow.
2nd Grade Blogger
Tales of a Fifth Grade Teacher
Mrs. Green's Blog Spot
11 Tools Training LJ
Teachin in Flip Flops