Well, this is an exercise in futility, because users don’t read.
But, as an exercise, here’s a collection of some of my pet peeves:
Questions should include any essential information about your problem –
it helps others work out solutions to your problem.1
If you want help with something that failed, describe how it failed.
If you got an error message, quote the error message in your question.
If you want help with a processing problem
(e.g., spreadsheet or text manipulation),
describe and give examples of your input, what processing you want to occur,
and what output you want to get.
Describe what you have tried and what results you have gotten.
Please don’t post images of text.
If at all possible, post a textual representation of your data,
as was done here and here;
use the Format Text as Table site if you want.
(Of course if your question concerns charts and graphs,
or fonts and/or colors,
it may be necessary to post images to supplement your textual description.)
Identify what operating system(s) you are using,
and provide version numbers of all relevant software.
The question title should be the title.
The title is not the first sentence of the question.
The body of the question should make sense
even if the reader ignores the title (and the tags).
As much as possible, your question body should be written
in the form of complete, correct English sentences.
Ideally, one of them should be an actual question
(i.e., it should have a “?” at the end).
Do not just describe your situation
and assume that we’ll guess what you want to do about it.
Avoid asking multiple questions in one question post.
Some of the above may need to be de-snarked a little.
Also, not all of these
fall under the “Information needed when creating a question” heading.
____________ 1 This is obviously copied directly
from Journeyman Geek’s answer.