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?)
When I started running study groups in college, the training included teaching how to learn student's names. The trick to remembering names is to say the name out loud, with focus on the name and the person at the same time. So, Joachim introduces himself, and you say "Joachim? Nice to meet you, Joachim!" Give the name and face enough time to sink into long term memory. If they don't introduce themselves, ask them their name, simply apologizing if it turns out you've met before.
Then, at the earliest good opportunity, reinforce the name. Using it during the conversation is good. Any time the topic goes in a new direction, or you or your interlocutor have a new idea, you say "So, Joachim, I have another way of looking at that..." or "Joachim, that is an excellent point." This is totally normal, but might not feel that way to a person who doesn't use names frequently.
Finally, it is minimally awkward to, at the end of a conversation, say to the person "Well, Joachim, it's been so good talking to you!" Or, if you've totally lost the name, say with a smile "I've enjoyed talking with you so much I've managed to forget your name!" And they will be quite pleased to remind you.
Not using people's names is like a microcosm of this thread--if you don't use the name, rightly or wrongly, you won't get affirmation or correction.
That all works if you have the capability of recognizing people but just have not practiced it. But you say specifically that you're not good with faces. A large number of people are partially or completely face-blind. Many (maybe most) don't realize they have differently functioning brains from the majority of people when it comes to faces. They often recognize people by their distinctive hair color or facial hair, by particularly large or small noses, chins, etc, or even in some cases, by learning the wardrobes of people they are frequently around. I read about one fellow with 4 young children and he is completely unable to tell them apart. So when one jumps in his lap, he hugs them and smiles and says, "So who are you, then?" His kids think it's a running joke, which is how he treats it, but it's the only way he'd know who he's got in his lap.
The point is, if you are not just "bad with faces" but instead face-blind, you may have to use other, more you-specific techniques for identifying people.
It wasn't until a couple of years ago that I first consciously noticed that I was incapable of using other people's names to their faces. I could do it with immediate family, and I could do it in third person "Howard was telling me..." I have since made strenuous efforts to get better at it, but it is still really psychologically difficult. That's also when I realized that it was almost impossible for me to leave a message on an answering machine. I'm working on that one too, but doing so is a serious effort. One of my roommates my freshman year of college had the same issues, but neither of us had a clue why.