Ask HN: What's the most valuable thing that you've ever learned?
Not just in terms of the latest framework. But interested whether it's a life lesson, concept, language, theory, tool or trait.
In terms of "clearly weaponizable in one's business/career", it's "measurement and leverage" from PG's wealth essay. http://paulgraham.com/wealth.html
In terms of "things which I wish I had known when I was much younger", I'll pick "In most things you will become the average of your five closest friends, so choose your peer group carefully." and "Dating is a sales and marketing exercise, with all that that implies." (Granted, telling myself that when I knew nothing about sales or marketing probably wouldn't have helped that much.)
If you have a little bandwidth to study Japanese prior to coming you'll get the highest bang for your buck from drilling self-introductions and basic conversations ("$ITEM kudasai.", "Yoroshiku onegaishimasu", "$LOCATION doko desu ka?") until you're blue in the face. Knowing just hiragana and katakana is of limited utility for navigation, since the places where it suffices will likely be English-friendly. (They're great to learn for mind expansion, just tough to operationalize as a tourist.)
That is, once you prove you're good at writing software, you can spend the rest of your career picking and choosing between employers as they suit your whim. There is very little you can do to sabotage your ability to find good gigs in this market (again, once you have established yourself as capable of doing the work).
That means you can treat work as a source of capital to bootstrap the rest of your life, picking it up and dropping it as need be. As you get more valuable, you can ramp down the number of months you need to work to save up the runway you need to last out the rest of the year. And you can spent the rest of your time doing whatever you want.
Personally, I spent a dozen years of that extra time traveling the world, climbing rocks, and building the software product business that's finally letting me skip the "employer" part entirely.
Start doing that when you're 25 and you will have a very fun 30s and 40s. Good luck!
It's very easy to see one's own shabbyness of clothes or behaviour. Well, because you're right there, up close, all the time. Now, do I recall any stains on someone's pocket or thread hanging down on a dress. Maybe, but it's rare, and I have to be looking quite closely.
This isn't license to be smelly and gross, not bathing and wearing clothes with great greasy stain all over them. Instead it's about the +/-5% of wiggle room we get from not being under the great sharp spotlight that it feels like we're under because, well, we're ourselves.
All that said, it's a great idea to pay special attention to one's self for an interview. Because you'll be under great scrutiny at that point, naturally.