I was a reader before I was a writer.
Here are some good reasons why you should hire me to edit your work:
I work at a newspaper. I'm not the editor, but I do check the seconds, and I often catch something that was missed.
I've been involved in writing critique groups since 2015. Not only do I check for grammar errors, but plot development, characterization, etc.,
I have Grammarly.
I have been an avid reader since...well, as far back as I can remember. I know what looks good and what doesn't.
As I said before, I'm an avid reader involved in several writing groups. If something seems off - plot structure, character development, lack of details, change of voice - I will notice.
If you are looking for more than copy editing, and you have a complete manuscript, consider having an in-depth, professional critique done.
"Editing should be, especially in the case of old writers, a counselling rather than a collaborating task. The tendency of the writer-editor to collaborate is natural, but he should say to himself, 'How can I help this writer to say it better in his own style?' and avoid 'How can I show him how I would write it, if it were my piece?'"