Okay, not easy. Easier.
You’ve probably heard that reformatting your word processing page single-spaced with narrow margins (making it look more like a book page) is one way to get fresh eyes on your work-in-progress. Even better, if you have a Kindle, try the personal document feature (Send to Kindle) to examine your manuscript. A different format helps you notice problems. For example, until I read my current project on Kindle, I didn’t see I needed another sentence in the first paragraph.
If you’re like me, you edit as you write. All advice is against this, but too bad, I can’t help it. Often when I finish a scene I examine it in MS Word’s two-page view. This is very handy for seeing across a lot of text, spotting sentence pairs with identical construction, the same word repeated too often, etc.
I hope at some point you read your text aloud, a tried and true method to reveal shabby writing. And here’s my newest technique:
Don’t just read your text aloud, record it! Then listen to it while you study your word processing page.
When you think you’re ready to publish, don’t. Submit your work to a critique group like critiquecircle.com. Not every bit of advice you receive may work for your project, but CC writers can teach you a lot. Some writers post several drafts of each novel whether they intend to submit it to an agent or self-publish.
Finally, if you self-publish, be kind to your book and hire an editor. It’s what every publisher does.