Surely every nature photographer has, at some time, photographed flowers. Really, is there any other subject that is more of a cliche? So here, obviously, the challenge is to see them in a new and / or different way.
My first encounter with a Passion flower at a nearby nursery was impactful enough that I went home, got my camera, tripod, etc. and returned to photograph it. The Passion flowers (approximately 500 species with at least as many hybrids) with their characteristic coronal filaments look (to me at least) like flowers from another planet.
While one should strive to be at least photographically competent with all kinds of flowers, it is inevitable that certain ones will appeal more than others. Some folks, for example, go nuts over the curvaceous intricacies of Orchids while I prefer the more angular structure of Passiflora. Until recently I was never big on Iris until I encountered an unfamiliar color variation. So of course, like other areas of life, it comes down to what most appeals to you.
Once you’ve decided on your subject, the next question should be: How much control do you have? Do you have to work in situ or can you cut the bloom and work with it in “your” world (and if you’ve cut the bloom, how long before it wilts). Assuming you can “control” your subject, the next thing I do is to hold it close, close one eye (so as to replicate my camera’s monocular vision), and turn it every which way to find the strongest composition. After choosing your subject, the next most important thing is the background: keep it simple, rather than cluttered or confused, is my advice. If you’re working in the field (or at home) it’s not a bad idea to have a (one meter or so) bit of black velveteen on hand or look for a naturally dark background like bark or shadow. Another great background is “aquarium” coral, spray-painted matte black.
Now that you have your subject and background, the third “tripod leg” is light. Light makes it Right. Or wrong, if you’re not paying attention to what’s going on (light-wise). Many flowers (but not all) look great with back-lighting so they appear to glow. Sometimes a reflector, improvised or otherwise, is useful. Sometimes diffused light or cloudy conditions are better. Usually a tripod makes sense. As much as possible crop with your camera. Simplify wherever possible (less is more). Edit ruthlessly. Bottom line: whatever works.