There’s no easy way to self-edit. Few people want to face their own work and ask: how can I make this better?
Sometimes editors can be expensive. Giving your work to a friend or family member doesn’t always mean you’re going to get the feedback you’re after. When you’re working alone, I find it helps to come up with an arbitrary rule.
My rule: don’t use “That.” As I self-edit work, I challenge myself to remove “that” as often as I can. Not just cut, but delete. Most of the time, “that” exists in excess - it can be flat out deleted with no change to the sentence. Other times, you may need to do a little rewriting to make the sentence work without using “that.” 100% of the time, the sentence is exponentially better.
Sometimes, though, “That” must persist. When the extraneous “thats” have been removed, the remainders are far more potent.
Create a completely arbitrary rule for yourself as you work through your edits and see what happens.
Maybe you edit so everything is presented in the third person, or the present tense. Edit out all of the commas. Or, add in more commas. Make it weird - what happens if no sentence is longer than eight words?
What happens if every sentence has at least eight words?
Self-editing with arbitrary rules forces you to step outside your usual style and forces you to adopt another mindset outside of who you are as a writer. Everyone writes differently; everyone reads differently. Arbitrary rules are a way to put on a different pair of lenses and consider someone else’s distortion.
The result of the arbitrary rules need not stick to the final publication. This is just an exercise. It is a way to keep you on your toes as you review your work. It is a way to grow your writing style.