This question was on a mailing list I'm on.
> Are there some guides to best practices specifically for plant photography?
Here's my reply:
you'll get lovely pics in the (far too) yellow light of evening,
you'll get nice shots when you manage to catch one sharp flower in a wafting lot on a (far too) windy day,
you'll get wonderful photos in the (far too) sharp color contrast on a sunny day,
and you'll get many of your best images on overcast windstill days.
If you want to use your photos for things beyond your own education, do
1) detail, 2) whole plant, and 3) stand. For every species, if at all possible.
Detail photos usually benefit from the sharp contrasts of a sunny day,
whole plant (or whole stand) photos usually thrive in the muted colors of an overcast sky.
Neither get all that good on a windy day, or on a rainy day, but if that's all you have, well, take pics anyway - just take more of them, cos you'll have to discard quite a lot.
With digital cameras, it's good to take a lot of photos of each species anyway, and then select at most 3 per plant. Unless, of course, they're all stunning, in which case, just use them all.
Get the sharpness right by taking a pic of one flower, and checking it on your PC screen, and taking another pic of the same flower, and checking that, and taking another, ... until you get it right.
I think it's best to use an SLR, cos there you can twiddle a lot of things (like shutter speed, ISO, focus, etc.) yourself - you're not dependent on the decisions of the programmer of your digital camera. But then, I've been using SLR's, like, forever.