My suggestion: take a crash course in etiquette by going to another city nearby, and then spend a few days walking around asking questions, or inviting people to do stuff with you, etc. Condition yourself to get used to the occasional weird look, learn what you can get away with, and possibly make friends with people you would otherwise never meet. If all else fails, drive out of the city and pretend the entire thing never happened. Or you will get some amusing stories to share with me when you get back. How can you lose?
I am only partly joking, my social skills are so mediocre I have seriously considered doing exactly this at some point. I might throw in some speed dating as well for good measure.
I do this all the time, with fantastic results!
A current example is my temporary move to Boston/Cambridge. I've walked around asking random strangers questions such as "If you could live anywhere in Boston, where would you live?"
I've received great advice, and made a few friendships and event invites from doing so!
I am beginning to suspect that it is surprisingly common for intelligent, competent adults to somehow make it through the world for a few decades while missing some ordinary skill, like mailing a physical letter, folding a fitted sheet, depositing a check, or reading a bus schedule. Since these tasks are often presented atomically - or, worse, embedded implicitly into other instructions - and it is often possible to get around the need for them, this ignorance is not self-correcting. One can Google "how to deposit a check" and similar phrases, but the sorts of instructions that crop up are often misleading, rely on entangled and potentially similarly-deficient knowledge to be understandable, or are not so much instructions as they are tips and tricks and warnings for people who already know the basic procedure. Asking other people is more effective because they can respond to requests for clarification (and physically pointing at stuff is useful too), but embarrassing, since lacking these skills as an adult is stigmatized. (They are rarely even considered skills by people who have had them for a while.)
This seems like a bad situation. And - if I am correct and gaps like these are common - then it is something of a collective action problem to handle gap-filling without undue social drama. Supposedly, we're good at collective action problems, us rationalists, right? So I propose a thread for the purpose here, with the stipulation that all replies to gap announcements are to be constructive attempts at conveying the relevant procedural knowledge. No asking "how did you manage to be X years old without knowing that?" - if the gap-haver wishes to volunteer the information, that is fine, but asking is to be considered poor form.
(And yes, I have one. It's this: how in the world do people go about the supposedly atomic action of investing in the stock market? Here I am, sitting at my computer, and suppose I want a share of Apple - there isn't a button that says "Buy Our Stock" on their website. There goes my one idea. Where do I go and what do I do there?)