Well and truly stated ... you might be a professional editor!
And quite a few people, while they are passionate about their work, aren't passionate about spending money on it with a professional editor. But they'll think about that editor, and start mining friends to do the job they think an editor does. A moderately good idea. Just, again, treat it like you're submitting to a publisher or an editor - cover letter, synopsis and sample chapters. Let those friends request more chapters to go over, talk to your readers, find out where problems are, fix them.
It is most tempting to hand someone an entire book to read. NEVER do that, if the goal is to improve the book. The more you give a person, the more they assume they have to consume, and they'll read it quickly and skip over the problems. One of my favorite indie authors aggravates the heck out of me by using ‘site’ instead of ‘sight.’ I wrote them about the issue and found out that I was the first to say something about it. None of their reader friends had ever mentioned it.
Issues like the improper use of a word will fall to the back of the mind, especially if the rest of the story is a great read. Have your friends ‘pay’ you for the next couple chapters by giving their views on the work, what problems they found and glossed over. The goal is to improve the work, entertaining friends is a secondary goal.