I've studied game theory and rationality, and I don't use game theory even when applying rationality to game design! I've used some of the nontechnical results (threats, from Shelling's book) to negotiate and precommit but that's about it. Has someone else used game theory in real life?

Unless someone else responds to this comment, my guess is that this topic is of greater interest to readers than it is of any use.

By "via rationality" I assume you mean "via logical argument or sound science", which is an absurd substitution. Rationalists should win. The Dark Arts therefore are a type of instrumental rationality. That said, I still disagree, at least for some irrational people (let's roughly say anyone I could convince to eating a food that gives them a stomachache).

They can be convinced they should study [instrumental] rationality, it just requires you present unreasonably large amounts of evidence and don't use logical inference or experiments. (And when I say unreasonably large, that's for people in college studying science. For merely average twenty-somethings, you may need to beat them over the head with solid bricks of evidence.) Caveat: I do not often interact with allegedly common people who don't meet the minimum bar of adjusting expectations based on (sufficient) observation, so this comment does not apply to such persons. It is still a useful comment.

I.e. look, I used this thingy called rationality and I made/saved thousands of dollars, got a boyfriend, and fixed significant mental problems. Seemed to work for me okay. You need to go REALLY overkill on the evidence for non-science folks though. Again, beat them over the head with it. Make it something that will help them personally, too. I've found it useful to get people to agree (not verbally and aloud, though that's an interesting experiment) that whatever mysterious method I used to I do that, it would be a good thing to learn, BEFORE I revealed that the answer is something weird or "educational" sounding. This second half is only slightly dark-artsy (consistency bias).

Did he say why he thought it was for people your (ChronoDAS's) age?

Check out most of behavioral economics. (I recommend Dan Gilbert on Ted, not linked to avoid trivial chances to waste time)

In AI, this is known as the exploration/exploitation problem. You could try Googling "Multi-armed bandit" for an extremely theoretical view.

My biggest recommendation is to do a breadth-first search, using fermi calculations for value-of-information. If people would be interested, I could maybe write a guide on how to do this more concretely?

I found that what reduced my low-value leisure time most was doing something incredibly fun, by explicitly optimizing for it. Then when I went back to i.e. reading webcomics, it seemed mildly repulsive in that it wasn't actually that fun. I suspect, but am not sure that, having a large amount of fun when you have fun 1) Reduces the amount of time you'll spend having fun, in that it satiates your quota earlier. 2) Causes you to consciously choose how much leisure time to have, because it's hard to default into really fun behaviors as procrastination.

I also tried 1) allowing myself to do anything I wanted, as long as I planned it at least half an hour in advance (if you have a pre-set quitting time this could help?) 2) Setting a timer to interrupt every 15 minutes and ask me what I was doing. One of my main problems was cost-insensitivity to time; playing a computer game for 5 hours did not feel almost any more a waste of time than doing it for 1 hour.

Please let me know if any of these work, so I know whether to recommend them to others in the future.

I suspect convincing people optimal philanthropy is a good idea is probably one of the most important things one could do. Maybe you should find out?

Find a cookbook, which often contains more fleshed-out recipes, instead of searching online. You can of course evaluate a cookbook for this property before you buy one. I find watching Alton Brown (Good Eats) helpful, in that he covers things too simple to be a recipe (eggs), mentions specific problems you might have, explains such things, and of course you can see it being done, which helps. He also explains some of the science behind cooking, which is fun. I assume other cooking shows fix many of these same problems (Julia Child? I haven't watched). I often cook Alicorn's recipes, and can ask her for help if something is underspecified. Finding a somewhat experienced cook to help (preferably in person) might be useful?

German recipes are even worse. They don't specify things like pans, oil, how to combine ingredients, or sometimes even baking temperatures. They're basically a list of ingredients and assume you know... well, more than I do. Plus I don't speak German very well, so I had a nightmare making the one recipe I properly translated.