I have a neighbour who calls in to see me 3 or 4 times a week. Some would find his style of conversation annoying; I find him quite amusing. He has enabled me to compile a list of 'rules' of how not to carry out a discussion:
1) The more you know, the more you realise you don't know and its converse: the less you know, the less you realise you don't know. This is close in meaning to the expressions 'empty vessels make the most noise' and 'ignorance is bliss'.
2) Don't be afraid to say 'I don't know' Don't pretend to have an answer to everything.
3) Consider the possibility that the person you are about to address knows more about the subject than you do.
4) No shin-kicking. Don't try to belittle your conversation partner(s) or score points against him (her). Go for the subject, not your conversation partner.
5) Try to make your brain work faster than your mouth so that you can avoid saying insulting or otherwise inappropriate thoughts.
6) Be careful if you play Devil's advocate. Make sure you really are exploring a valid opposite view rather than just being argumentative. Avoid playing Devil's advocate to increase your prowess: it often has the opposite effect.
7) A good discussion needs good listeners as well as speakers. Don't cut off your partner before he/she has finished; it sends a message that you are not interested in what your partner is trying to say.
8) Take only your share of the conversation. Interviewers should take less than half the conversation: they are there to guide the interviewee, not to sound off their own views.
9) Keep to the subject. Don't hi-jack a conversation to make a point you want to talk about that is not relevant to the conversation. In particular, don't put words into your partner's mouth, misquoting him/her, or otherwise set up a straw man so that you can demolish it.
10) Remember where you are. How would you feel about someone coming into your home and expressing disapproval of some feature of it, or grabbing your phone without asking, for example?
