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. First and foremost, 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 a lot 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?

If you want to keep as much in focus as possible, you should consider all the ways that you can control depth of field. As you probably know, your camera's aperture is the primary way you control depth of field. For close-up flower photography, I highly recommend switching your camera to Aperture Priority mode. The larger the f-number, the deeper your depth of field will be (but, unfortunately, the longer your exposure time). You'll need to balance the depth of field with the shutter speed so that you don't accidentally introduce camera shake or blur in your shot.

A less obvious way to control depth of field is the lens's focal length. If you are using a zoom lens, try setting it wider. Bottom line: the longer the focal length, the shorter the depth of field.