What defines “professionally taken” photographs? One of the first things a lay person tries to do is define the quality of the equipment used to take the photo, but the fanciest camera in the hands of someone inexperienced will only take photos that look inexperienced. An enthusiast tries to define the qualities of the image—color, composition, etc, and this is closer to the truth, but anyone can get lucky and sometimes does. Perhaps they will try to define attitude and artistry, which is yet closer to the truth, but still a good attitude and appreciation of art can only get so far in the actual creation of images.
A professional uses the habits of mind—the combination of technique, preparation, repeatability and eye—in taking professional images. The mind guides the head which guides the eye. The best photographers already have ideas on what they think they want to see, can guide subjects to look their best, and yet are still able to improve on this with opportunities to discover more in the scene.
Eye first. Apply your artistic eye to the image. If the bride is about to throw the flowers, you position yourself to perhaps capture the look on her face as she throws—or would it be better to catch the bouquet of flowers, streamers awry, as it sails over her head? Make a plan.
Preparation and technique: did you consider ambient lighting and are able to position yourself for a cross-shot where illumination favors the people in the image, their surprised and eager looks? Is your flash metered? Focus preset? Are you writing to a CF card as well as SD? Are you on auto-white? Set ISO higher but not too grainy. Get out of focus lock. Better get that 50 on front instead of the 85 prime, this is going to be a wider scene. Preparation can go much further than this.
Repeatability: Rinse and repeat, according to your art. This is hard in image-making. Try it. It’s easy to occasionally get lucky in picture-taking, but to take different clients with different feelings on different days and give results in a measurable way; that takes resilience, patience, control of equipment and technique, and an application of your eye with unique preparation.