I’ve found that I’m pretty good at editing someone else’s stories, but not my own. Of course the solution is to pretend I wasn’t the one who write the story, but that’s easier said than done. The first trick to achieving this is to just let my manuscript sit for a little bit so I actually do forget what I wrote, this way when I do go to edit, it’s with open eyes. When I go to edit I want to look for inconsistencies in the story and simple mistakes.
Now this is where things get a little hard. You have to go through your manuscript line by line editing, and almost make it a game to find as many mistakes as possible. If you don’t find many, go through it again. This is going to be a lot of work, but I promise you it will make you a better writer. The more scribbles you have on your page, the better. This way when you hand your manuscript to your editor or beta reader they won’t have as much to edit And can give you better quality feedback. After all, if you give them a sloppy manuscript, they want to edit for you again.