What simple rationality techniques give the most bang for the buck? I'm talking about techniques you might be able to explain to a reasonably smart person in five minutes or less: really the basics. If part of the goal here is to raise the sanity waterline in the general populace, not just among scientists, then it would be nice to have some rationality techniques that someone can use without much study.

Carl Sagan had a slogan: "Extraordinary claims require extraordinary evidence." He would say this phrase and then explain how, when someone claims something extraordinary (i.e. something for which we have a very low probability estimate), they need correspondingly stronger evidence than if they'd made a higher-likelihood claim, like "I had a sandwich for lunch." Now, I'm sure everybody here can talk about this very precisely, in terms of Bayesian updating and odds ratios, but Sagan was able to get a lot of this across to random laypeople in about a minute. Maybe two minutes.

What techniques for rationality can be explained to a normal person in under five minutes? I'm looking for small and simple memes that will make people more rational, on average. I'll try a few candidates, to get the discussion started.

Candidate 1: Carl Sagan's concise explanation of how evidence works, as mentioned above.

Candidate 2: Everything that has an effect in the real world is part of the domain of science (and, more broadly, rationality). A lot of people have the truly bizarre idea that some theories are special, immune to whatever standards of evidence they may apply to any other theory. My favorite example is people who believe that prayers for healing actually make people who are prayed for more likely to recover, but that this cannot be scientifically tested. This is an obvious contradiction: they're claiming a measurable effect on the world and then pretending that it can't possibly be measured. I think that if you pointed out a few examples of this kind of special pleading to people, they might start to realize when they're doing it.

Candidate 3: Admitting that you were wrong is a way of winning an argument. There's a saying that "It takes a big man to admit he's wrong," and when people say this, they don't seem to realize that it's a huge problem! It shouldn't be hard to admit that you were wrong about something! It shouldn't feel like defeat; it should feel like victory. When you lose an argument with someone, it should be time for high fives and mutual jubilation, not shame and anger. I know that it's possible to retrain yourself to feel this way, because I've done it. This wasn't even too difficult; it was more a matter of just realizing that feeling good about conceding an argument was even an option.

Anti-candidate: "Just because something feels good doesn't make it true." I call this an anti-candidate because, while it's true, it's seldom helpful. People trot out this line as an argument against other people's ideas, but rarely apply it to their own. I want memes that will make people actually be more rational, instead of just feeling that way.

Any ideas? I know that the main goal of this community is to strive for rationality far beyond such low-hanging fruit, but if we can come up with simple and easy techniques that actually help people be more rational, there's a lot of value in that. You could use it as rationalist propaganda, or something.

EDIT: I've expanded this into a top-level post.