I am never sure that I twitter correctly, but the only "rule" I've seen out there is not take up the whole page with constant tweets. I have to amen that one - that definitely categorizes you for an "unfollow" in my book. 

What mystifies me is people who use Twitter w/out blogging, too. To me, it all goes together, like peanut butter and jelly. For me, Twitter is a way that I get to know a blogger more - that's all I really care about!