Michigan macrophotographer Mike Moats' book "Tiny Landscapes" contains beautiful images and brief, useful explanations. He usually shoots at a high f-stop. Here's a website:
tinylandscapes.com
I also have been pleased with Ross Hoddinott's "Digital Macro Photography."
Also, I love the Macro thread within
BirdPhotographers.Net - It Ain't Just Birds. (Many of the photos in that thread are NOT of birds.) Mike Moats is a moderator of that thread. He and other photographers provide helpful suggestions — plus praise — to photographers who post in that thread. Visitors to the website may browse without charge, but there's an annual membership fee for some additional privileges.