Talk very little. Bonus: reduces potential opportunities for accidentally saying stupid things. (People who speak only to convey information are smarter than people for whom talking is its own purpose.)
I perhaps should work on this one. It might improve my signal/noise ratio.
Your list is quite wisely written.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
(I plan to make these threads from now on. Downvote if you disapprove. If I miss one, feel free to do it yourself.)