This seems like very good, thorough, general advice. However, I wonder how many of us (heterosexual males reading Less Wrong) have romantic preferences that are as general. I realize that the "reading Less Wrong" part of that descriptor wasn't specified in the question, but it seems implied.
In general, a heterosexual man might describe the set of his potential romantic partners in the following way: a woman whom he finds physically attractive, with whom he shares interests, and with whom his personality is compatible. (That the woman is currently single is also important for many, including myself, but I recognize that it's less general than the former three, given the existence of polyamory/fidelity.)
However, for myself, I would add to this a fairly strict qualifier, that the woman is an atheist. I simply don't feel that I would be able to be emotionally intimate with a woman who holds an irrational, i.e. religious, worldview. Atheist doesn't necessarily mean rationalist, but religious almost definitely means irrational, i.e. P(rationalist|atheist) >> P(rationalist|religious), and even more so for P(would be open to rationality|atheist). I find it to be a sound heuristic that prevents me from embarking on relationships very likely doomed to failure. I doubt that I am alone among LWers in taking this into account.
Unfortunately, I have found it really damn hard to meet atheist women. I can count on one hand the number I have met in college. A large part of that is that I attend a science/engineering university which has a student body comprised of only ~30% women, but even then, my expectation before entering the university was that a population self-selected for interest in science/engineering would have a larger proportion of atheism than the general population. That expectation was not met by reality, and I recognized that I was confused, but trying to resolve that confusion (see below) didn't appreciably help my goal of meeting atheist women.
Studies have shown that women tend to be more religious than men. I also hypothesize that women who do select a science/engineering university are more likely to have gone to a private high school (76% of private schools are religious). As women tend to be socialized away from an interest in science, a stronger educational program than exists in the average public school might qualify as a "push" to counter that trend. I have met a fair number of women at this university who went to a religious school, but the sample size isn't large enough to confirm that hypothesis.
In any case, the problem remains: atheist women seem to be hard to find. The types of general activities you've suggested are good for socializing, but unlikely to have a larger-than-average atheist population. Are there activities similarly strong in socializing that would have a larger atheist population?
(Note: I don't mean to slight the obvious effort you put into this post; it's just that my own issues on this subject, and I suspect some others' issues as well, are more involved than just social awkwardness/inexperience.)
The reason to go into environments where you interact with a lot of women isn't only an issue of having a lot of opportunities. It's also a matter of practice.
Even if you don't like to date the woman at a dance class the class will still teach you basic skills about interacting with women.
If you don't have the practice with regularly interacting with women than you are unlikely to have success when you find a woman who would be a good match because she fulfills your criteria.
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?)