Pete: You’ve started a great thread, and have generated from your respondents much useful advice. Could I just add my two-cents’ worth?
There is a tendency to assume that everyone who engages with you is arguing in good faith. I’m afraid that’s not so. You can waste a lot of time and energy dealing with correspondents who seem to be deaf to everything you say, and unwilling to do the real work of thinking, reading and reflecting that’s necessary to a genuine conversation.
Michael McCloud’s Secrets of Libertarian Persuasion, and his More Secrets of Libertarian Persuasion have very useful hints and strategies.