Proofreading our own writing is hard because, well, we wrote it. We tend to read what we think we wrote and not what we actually wrote.
When I first write something, it usually isn't that great. That doesn't worry me, I want to get ideas down and avoid staring at a blank screen. I write a few pages, create a pdf, proofread it, and immediately rewrite the parts I don't like or that have blatant grammar errors.
This type of proofreading isn't enough though.
The next day I work on the book, I reread what I wrote the previous day, hopefully after forgetting most of it. I'm able to improve the quality to the point where I'm not ashamed, or perhaps even proud, to show it to reviewers.
This second proofreading also helps me get back into the zone for writing the next section and helps each section flow into the next one. I find getting into the zone for writing much hard than getting into the zone for coding so I feel this trick goes a long way.
I always proofread my previous day's work before writing. Sometimes, I even proofread previous work from a few days. By the time I "finish" a chapter, I've probably read it five times - and reviewers still find things!