Lost my Tweet

So, I've really been struggling with how to use my Twitter account. I often think about posting to Twitter, but I haven't determined who my audience is (students? potential students? friends? colleagues?) and what my purpose is (recruitment? dialogue? information?). Even my Twitter name reflects this lack of clarity; I've listed just my last name. Of course, these are not problems limited to Twitter. They are classic writing problems. You can't write until you know why you are writing and to whom.