I recommend you visit the blogs you enjoy, and begin by following those folks first; most have Twitter accounts. On Twitter itself, you can also search for topics of interest, which in turn will direct you to some folks to follow.
Definitely take it slow, preview the posts of tweeters before following, and don't be afraid to unfollow someone whose tweets you find annoying, offensive, or unproductive.
I'm @keithschoch, and I tweet about teaching with picture books, teaching with novels, and to a lesser degree, online technology apps for instruction. Check out the people I follow, as most of them are way more interesting and intelligent than me. Than I? You see what I mean...
A couple blog posts that you may find helpful in your classsrom: