Not Going for the Face
One of the most important things I believe one should do in arguments is to allow for the possibility of your winning the argument without costing the other person too much face. Most people care a lot about face, even though they probably shouldn't; unless your debate is on behalf of a third party, or primarily for onlookers, if you want to actually convince/influence someone, even partially, you should keep it friendly, show you're willing to give when warranted, and if/when you make headway, be as charitable as humanly possible to their person (even if not necessarily their argument).
I'm always trying to figure out ways to do this better.
It's sadly often impossible to have a charitable conversation with people in activist communities because most of them are rotten enough that if you disagree with them, they'll have a variety of ways to argue that they shouldn't even be listening to you, have a bunch of names to call you, etc. If you find such things interesting, you can watch these antibodies when you see bad discourse standards move from one person to another (this whole "argument from positional privilege" thing in third-wave feminism is a great example). Fortunately, there are good ways to unplug those arguments too, but unfortunately they tend to be very jarring for the person who only knows how to argue with them.