Fitz,
You invited me to post another one so I will post one more. This was taken at f/14 and I rarely go below f/16 but I do at times accidentally hit the command wheel changing my f stop and sometimes my shutter speed. This one was also shot at ISO800 and if I remember correctly I did use a higher ISO with some of my shots so I could dial down the flash avoiding hot spots. I'm sure you've been told that with macro manual focusing is the only way to go but many of my macro shots are auto focused as this one was. With my 180mm lens I use two SB600 speedlights with one on each side of the lens with a macro flash bracket. With my 90mm lens I can get good shots using one speedlight on a flash bracket that extends above the camera. Providing your own lighting allows for much faster shutter speeds and hand holding the camera. With slow shutter speeds a tripod is essential and you'll still get blurry images from subject movement.
A good technique with manual focusing is to hold the viewfinder to your eye and move in on the subject. When precise focus is attained immediately press the shutter button and providing your own lighting which will allow a fast shutter speed your shot will be sharp & crisp. Macro is not that difficult if you follow a few simple rules.
Jerry