So, one more litany, hopefully someone else finds it as useful.
It's an understatement that humility is not a common virtue in online discussions, even, or especially when it's most needed.
I'll start with my own recent example. I thought up a clear and obvious objection to one of the assertions in Eliezer's critique of the FAI effort compared with the Pascal's Wager and started writing a witty reply. ...And then I stopped. In large part because I had just gone through the same situation, but on the other side, dealing with some of the comments to my post about time-turners and General Relativity by those who know next to nothing about General Relativity. It was irritating, yet here I was, falling into the same trap. And not for the first time, far from it. The following is the resulting thought process, distilled to one paragraph.
I have not spent 10,000+ hours thinking about this topic in a professional, all-out, do-the-impossible way. I probably have not spent even one hour seriously thinking about it. I probably do not have the prerequisites required to do so. I probably don't even know what prerequisites are required to think about this topic productively. In short, there are almost guaranteed to exist unknown unknowns which are bound to trip up a novice like me. The odds that I find a clever argument contradicting someone who works on this topic for a living, just by reading one or two popular explanations of it are minuscule. So if I think up such an argument, the odds of it being both new and correct are heavily stacked against me. It is true that they are non-zero, and there are popular examples of non-experts finding flaws in an established theory where there is a consensus among the experts. Some of them might even be true stories. No, Einstein was not one of these non-experts, and even if he were, I am not Einstein.
And so on. So I came up with the following, rather unpolished mantra:
If I think up what seems like an obvious objection, I will resist assuming that I have found a Weaksauce Weakness in the experts' logic. Instead I may ask politely whether my argument is a valid one, and if not, where the flaw lies.
If you think it useful, feel free to improve the wording.