My number one editing tip is - Never do it all by yourself as a writer. The eyes can never see all that the brain can conceive. No matter how well you write, you can never pick out all your errors, as you know the story too well, know exactly what’s going to happen and therefore, see what your mind tells you to see.
As for writing, don’t assume you’re a brilliant writer just because your dearest and nearest or your egotistical self tells you that you can write. Raw talent, no matter how amazing, is still what it is, Raw. It needs thorough cooking to become palatable. So, take a writing course. It doesn’t have to be a degree. It will teach you the basic rudiments of writing and the discipline needed to stick to it and make your natural talent even more incredible. Good luck and may fame and success shine on all us slaves of the ink.
Write your first draft as you would an exam: quickly; just get it all down. Then, edit at a languid pace. The slower, the better.
When you edit, think deeply about how sentences sound when they’re read out loud, or in the mind’s voice. Consider rhythm. Avoid repetition. Simplify. This goes as much for prose as poetry.
Writing is a kind of fitness: work out every day.
Write. Put it Down. Leave it. Come back much later. Cut. Repeat.
Leave as long a gap as your deadline allows between writing and editing. That way, your ego does not get in the way when it is time to cut the crap. The more crap you cut, the more the flawless heart of your story will shine through. If you start editing too early, your brain will try to trick you into thinking that the crap is flawless. And it never is.