Copy Editor Quick Tip #2: Review a Hard Copy of Your Manuscript
It's a fact that looking at something from a different angle gives you new insights. For your publisher and editors, who are looking at your book for the first time, each flaw is already obvious. (That's why having somebody else look at your work is an absolute must before publishing.) But since you've been staring at your manuscript in your word processor for so long, a good way to see it from a new angle is to print it out and read it in bed.
No doubt you've found mistakes and typos in published books this way, reading in the evening before you quit for the night. I know I have. Give your book the same treatment, and you'll be surprised how many their/there-type mistakes you can catch.
(Btw, my son was born at the end of May. We couldn't be happier to meet Daniel in the flesh. He's three and a half weeks old today.)