There’s no single right way to shoot flowers, but the most common approach is to use a macro lens or your camera’s close-up mode. Macro photography allows you to fill the frame with the most interesting parts of the flower while weeding out the background.
Macro photography, especially when shooting flowers, has a unique set of challenges. Perhaps most important, the depth of field is quite narrow. Depending upon how close you are to the subject, it can be less than an inch. That means you need to think about the composition of your shot. Do you want most of the flower to be in sharp focus, or only part of it? Is it okay for a lot of the frame to be blurry?