@elemtilas recently proposed in this comment that we, as a community, establish some guidelines for editing. Since I do quite a bit of editing, I have decided to accept his challenge and make a preliminary Ten Rules of Editing.
Eliminate objectionable content wherever you find it. Foul language, innuendo, and slurs should not be countenanced by any member of this Stack.
Do not edit in spite of the express wishes of the originale adjunctor. If the OP says they want to word things a specific way, that's how they want it. If you really think your way is better, propose it in a comment.
Do not alter the meaning of a post. Style must always bow to Meaning; sometimes an ungainly style is the only way to express the meaning.
Fix grammar whenever possible. Information presented here should be easy to read, so that people can glean necessary information. Therefore, you should expeditiously fix the following: (more things can be added as necessary)
a. lack of appropriate capitalization.
b. Capitalization Where It Doesn't Belong (be careful about this one, though; sometimes it's significant)
c. Incorrect! usage? of, punctuation/
d. Yesterday, my mother came over and told me about this really interesting but obfuscating backstory. It doesn't really contribute, but I wanted to tell you anyway because it's really interesting...
e.Giant walls of text. Don't worry, I'm not going to unleash one on you.
Mark important points with bold-face. Doing so helps to make the point of a post more clear.
Eliminate all instances of non-shortened bare URLs (e.g. https://worldbuilding.stackexchange.com/) They are ugly, and add unnecessary length to posts.
Keep post lengths to a minimum without altering their meaning. While expository length is good, verbosity is not.
Thou shalt edit when appropriate. These rules are useless if nobody actually does any editing.
Additions and changes are welcome, but please try to keep in #5.e; rules are good, but only so long as someone can read through them.