..you may be asking yourself: are there times I shouldn’t tweet? Well, yes. These may seem obvious, but I have seen may people break the guidelines listed in this posting on the blog Meg’s Single Step. There may be more than this, but start with the Top Ten Worst Times to Tweet. Incidentally, what goes for tweeting goes for blogging and any other digital communications.
(Thanks to Andy Piper for the tip.)
Smart People I Know 
Personally, I’m not sure that those are all hard-and-fast rules. There’s an element of authenticity that would be lost if you followed every one of them. I think they are good guidelines, but it’s fair to “break” some of them sometimes.