I notice that the Guardian has a conference on “How to use Twitter effectively”. For much less money, let me offer my version.
1) Think of something.
2) Type it.
3) Realise it’s way more than 140 characters, and edit it down until it fits.
4) Review to see if you’re likely to be sued.
5) Review to see if you’re likely to be ridiculed.
6) Review to see if anyone’s likely to be interested.
7) Review to see if lots of other people have already said it. (Although that’s ok if you really want to express your support for something. But bad if you thought you were being funny or original).
8) All ok? Re-read it to see if it still looks like you’re at least semi-literate.
9) Press ‘Tweet’.
10) Wait for the deafening silence as no-one cares.