I have photographed orchids for a few years now and worked with black cardboard and windowlight as a "setup," and I´m pleased with the results. Unless you are working with tiny species (Lepanthes, Pleurothallis and similar), or want to do extreme close-ups, you need no macro. Keep bellows exposure compensation and reciprocity data handy. My only non-technical advice is: start working with species with simple shapes (Phaelenopsis, Vanda, Lycaste), especially in B&W, until you get the hang of what you want your images to look like, before you venture into photographing the more bizarre plants. It takes time to tune the eye and find out how to look at your subjects to bring out their exotic character, instead of producing just another flower photo.