How to write a Stack Exchange Question?

Asking a good question is a lot harder than writing a good answer, even if writing a good answer likely requires more research and more experience, which makes them very valuable. So let's have a look at what's important in writing a good question as opposed to an acceptable question. You already mentioned the most important resources that help you writing an acceptable StackExchange question, so I'll skip the advice you would find there and jump to the things you seemingly deemed important. Please note that a lot of this is subjective and depends on the specific site and the current "trending" topics and style there.

Title

You mention that titles are important. No question here, so I'll skip this. Or should I...? I am not entirely sure. You seem to have identified this incredibly important aspect but feel like there is still something left that needs to be said. A "perfect" question would make clear what you are expecting from an answer with that bullet point. I'll just add a bit to this because it is incredibly important.

Titles are what differentiates a good from an acceptable question at first glance. If you spend some time of StackExchange you will notice a pattern of really, really bad questions that often have similar problems. One of them being that their titles are not good. They write everything in lowercase, they write a topic like "Writing a StackExchange question" instead of a question like "How to write a StackExchange question?", they don't use any punctuation, there are typos, the vocabulary and site-specific terms are wrong, they are asking for an "opinion" or "ideas" right there is the title... Not every bad title belongs to a bad question, but most bad questions have a bad title. That means that if you, as a long-time user, ignore questions with a bad title you are automatically ignoring most bad questions. You also ignore some good ones, but you accept those false-positives for an overall more pleasant personal experience.

As long-time users are the ones with such an experience and at the same time those that provide most of the answers and feedback in general a question with a bad or even a mediocre title will receive far less attention than a question with a good title - no matter how good the question body is.

Having a good title that tells people what your question is about in a concise way is probably the single most important thing in creating a good question that people will want to read and answer.

Formatting

Markdown can be difficult to use in the beginning. I remember how I struggled with proper lists because you need an extra empty line between the text and the list for the "-" at the beginning to be recognized. And then you need a space after it to really make it a list. And then I tried to use HTML because I knew how to use that and people told me not to use it because it messes up the site for people using a screenreader. And not having alternative texts for images makes a question or answer basically unusable and frustrating for people using a screenreader. And then I tried to have a simple linebreak. Not a paragraph. Just a linebreak. For which you need two spaces at the end of a line before hitting Enter once.

It was difficult...

And this leads to me, as a member with more experience, to know that people in the beginning need some help. But it also needs me to know that people who use proper formatting have spent some time in getting to know the site they are working with. They try to get used to something that is not often used outside of the IT business and can be quite frustrating at times. They try to make their posts easier to read for me, someone who might be willing to answer their question and help them. It makes me feel better when people use proper formatting. That's why it's important.

What exactly constitutes proper formatting is difficult to say. It depends on the question, it depends on the writing style and it depends on the site you are on. Many people outside of StackExchange would argue that my use of italics is not proper. I nearly never use italics. But if you look through this answer up to here I've already used it quite often.

Why is that?

On StackExchange many people try to put emphasis on important things or to denote that something is not to be taken literal. Bold face and putting something into quotes are two of the more important ways to do this. But bold text kind of screams at the reader, which is why I noticed many people who are on the site for a longer time will use it sparingly. I, for example, mostly use it for summaries like in this recent answer of mine or in headers. You should definitely use italics and bold face. But try to use it where it adds value to your post and when possible use it sparingly. When in doubt use italics over bold.

It's also important to be aware of some of the more rarely used ways to format text. Like adding citations. For example look at my answer to the question How do you write a Stack Exchange answer? (hint: this way of phrasing it and adding links is also part of the topic "formatting"):

Adhere to traditional styles

On RPG you can find that many people refrence guides and rules in a specific style, by mentioning the book name and page number and then using the citation markdown with added emphasis on the names of an ability/ rule/ ... and the important words on which they focus later.

I've seen other sites use a style where you first cite the text and then add something like:

- The Book from The Author (Link: Link)

If your formatting looks like every other question on the specific site it will be easier for people to read and to find the most important points.

And another thing about formatting is to know when not to format something. If you look at the source text from this answer, specifically the last citation example, you will notice that I escaped the "-" so that it will not display as a bullet point, but instead as a dash.

If you use such little, more difficult, things I know that you have spent some time with markdown and put effort into your question. That makes me more likely to try to answer it. Which leads to more people seeing it and answering it.

Effort

Effort is difficult. The best thing to do is to link to similar questions on the site or maybe one or two Google results and say "I've seen this and that and they don't answer my question because reasons". Or even say "I couldn't find anything here and on Google with this query: Example query". It shows that you did your research, it gives people a starting point on what not to search and what not to talk about.

This question for example did a pretty good job with that. But maybe you could mention How do you write a Stack Exchange answer? and your previous question How to write a Stack Exchange comment? to show that this is basically the continuation of a series.

Which is an interesting thing in itself. Often the first one or two questions of a a kind of "series" of questions are interesting, but after that there is a sudden breakdown where people are bored and want something new. Sometimes the hype can last for a long time. I've seen that especially on WorldBuilding.SE, but other sites show such patterns from time to time, too. This question looks quite good to me and reminded me of the older question about answers that I've answers, but then again I haven't seen your comment related question before. Otherwise my interest in the question might have been lessened, too.

Ease of Communication

Just as there are certain formatting styles there are certain ways to communicate things. If I say "Square-Cube Law" every regular on WorldBuilding will know that I want to say that a animals can only grow up to a certain extent in real life. For the reason see Wikipedia:

If an animal were isometrically scaled up by a considerable amount, its relative muscular strength would be severely reduced, since the cross section of its muscles would increase by the square of the scaling factor while its mass would increase by the cube of the scaling factor. As a result of this, cardiovascular and respiratory functions would be severely burdened.

That's a standard comment under basically every "Anatomically Correct" or similar question. It's so standard that I don't even need to look at the comment section to know that someone will have commented about it. That means when writing a question about animals I need to write that people can ignore the Square-Cube Law. Otherwise someone will provide an answer like "It's not possible, see Square-Cube Law" while I am talking about fantasy animals. Not helpful.

By reading many questions on the site I am posting and in the topic I am asking about I can anticipate things like that and make it easier for others by saying they can ignore that aspect. This applies to every StackExchange site.

You need to be an expert about writing a question on the specific site you are posting on if you want a really good answer. You don't need to sound like a professor in the field, you need to sound like you know the standard phrases on the site and did some reading about the topic here. You will notice patterns. Make use of them.

Other stuff

It's often a good idea to write a concise, easy-to-understand question first and then add a "Longer version". That way people can skim the easy version to see if they are generally interested enough in the topic to read your question and maybe provide an answer before deep-diving into multiple pages of question body. On the other hand if you only have a very short version people might be missing some details. You will often see comments on StackExchange sites about missing details. Striking the right balance is difficult and requires practice. It depends on the topic, the site and your writing style. If you've read so far you have probably realised that my writing style is the opposite of concise most of the time. I prefer long texts with lots of information and on a lot of sites I regularly frequent people like this style especially in answers. Not so much in questions. That's why I need an additional small extra paragraph or a bold face question at the start or end.

I've also notices that when I am writing longer questions it's a good idea to start with a paragraph that is only one or two sentences, not much more than my title. Then I write the real, long question. And in the end I provide another paragraph with the question. This sounds like useless repetition, but it helps to keep the main question in the mind of the reader and show that I am really interested in this specific instance, not in something else that someone might have interpreted from my longer text. People tend to get hung-up on some small details, especially when answering longer questions.

And if you can make your question fun to read and fun to answer it will help a lot. People are mostly on StackExchange to get some help every now and then and to have fun reading and writing about their favourite topic. Everyone you normally encounter is someone sitting in front of their computer at home using StackExchange as a little hobby to unwind from time to time. You don't want your question to look like a joke question because people will think that you are making fun of them, which means you are making fun of the time they are spending to help you, but a little funny content has never hurt. For example here I made my question title look like the start to a joke, which people really liked: A witch, a vampire and a pixie meet in a bar and talk about tomatoes eradicating humanity. I knew that for story-identification question on SciFi.SE you don't need a "question" and so I decided to use this instance I remembered to make the title look like a joke, even if the question body was a real, normal story-identification request.