Not defining your subject in the image: Emphasize what interested you in that flower. Is its shape, color or pattern that made you choose it to photograph? Were you attracted to its abstract or graphic element?
Deep Throat ExposedBearded Iris in purple and blue lavender frontal on slant.VelvetCalla lily macro in B&W.
Having the flower dead center: Unless the symmetry is what you want to emphasize. The rule of thirds is popular for a reason and recommends placing your subject at the intersection of one of these 4 lines. Emphasize a curve, perhaps.
Monet IrisJapanese iris imagined as painted by Monet in his gardens.
Cluttered or distracting backgrounds: Either clear the surrounding area, shoot against a solid background or use a telephoto lens at a distance from the flower (180 to 300 mm) which is then far from the background. Basically the lens needs to be closer to your subject that the than the subject is to the background. The background will then become blurred if using a more wide-open aperture. Or you could use a macro lens close to the flower but with the background at a distance.Remember, depth of field is different with macro. As magnification increases, depth of field decreases; so the closer you are the less depth of field you would have. Therefore, you can emphasize what you want to have the viewer focus on.
Choose a clean and undamaged flower: Unless that is the story you want to tell. This will save time in post processing.
Shooting in mid day: Unless you shoot under a transparent reflector or under a cloudy sky.Mid day sun will be harsh and produce poorly exposed photos with too much contrast and low in saturation. If you shoot up, you can enhance the glow of the sunlight and have the blue sky as background. Leaves and flowers will reflect light which can be improved by use of a polarizing filter.
To the Sky