Self-publishing doesn't mean you have to do everything yourself. If you want to publish a book you can be proud of, you’re going to have to engage with people who have experience in producing books. One of those people is an editor. Yes, you’ll probably want to spend as little as possible on outside editing, so that means you may want to do as much self-editing as you can before you send your manuscript out for an editing quote.
One of the ways to make self-editing more productive is to be a master of your tools. Take advantage of the power of your computer to help you spot problems. Editors use certain tools to speed up their work and save you money, but you can use them first to present a cleaner manuscript to the editor.