- Use c, a, b respectively to denote elements of sets A, B, C
- If, in a moment of weakness, you do refer to a paper or book for a result, never say where in the paper or book the result can be found. In addition to making it difficult for the reader to find the result, this makes it almost impossible for anyone to prove that the result isn't actually there.
- Begin and end sentences with symbols wherever possible. Since periods are almost invisible (and may be mistaken for a mathematical symbol), most readers won't even notice that you've started a new sentence. Also, where possible, attach superscripts signaling footnotes to mathematical symbols rather than words.
The annoying habit: I used to write A = B = C when what I meant was B = A = C. These statements are both true in the same contexts (they have the same "reference") but mean different things; the former says A is B [for some reason] and B is C [for some other reason] so A is C; an = sign implies an argument. Rob Benedetto wasn't very forgiving of this habit. What's always struck me as odd, however, is that I'd naturally put the chains of equalities in the wrong order. It seems like one should naturally get the sequence right in the course of making the argument, unless one actively tries to screw it up.