Armorama (http://www.armorama.com) has a forum on model/dio digital photography.
But here are some basic tips that hopefully will help:
use a TRIPOD. The slightest shake (especially in macro/"Flower") will be magnified, =blur, = bad.
Shoot outdooors (preferably on a bright but semi-overcast day) will give you lots of bright free light
If you shoot inside, a little light behind the model helps too ("kicks" it away from background, adding depth and separation)
A reflector or some kind of "fill" light helps- even just some large whiet card, brings out details in nooks and crannies
using a tripod, take various shots form same set-up, just switching focus inmacro, and combine in a photo editing program
Angle helps..try to be the same height/angle as if you were a scale person taking the shot
Good luck, and post a few pics!