If I were a customer looking to book an event photographer, having the knowledge and ability to recognize which professional was best suited for my photographic needs would be very important.
My best recommendation for booking the right photographer for you is to study the location during the time at which you are to have your portraits or event photographed. Review the work of the photographers you are considering booking and compare the images each photographer took at locations similar to your venue's situation.
For instance, say you've just booked your wedding venue and you're planning on a beautiful New Year's Eve wedding at a luxury hotel with a great view of the fireworks show they'll be having at midnight during your reception. Now, you're looking to book your wedding photographer and here are 3 photographers under consideration.
The work of Photographer A has all been photographed outdoors during optimal sunlight hours and is beautiful. However, there are no examples of them using a light source other than the sun.
Photographer B's work, shows photographs indoors using flash. People are in focus, there is no red eye and the color of the photographs looks natural. Not to mention, you love their style!
Photographer C displays work that is indoor and outdoor using both available light and lighting equipment. Their photographs are creative and it is easy to see they know what they are doing.
So, who do you choose?
Photographer A is not a good choice, as they do not show experience or capability photographing in the situation you require. Photographer B and C both show the ability to create quality work in situations similar to the environment in which your wedding will be held. Photographer C holds a technical advantage because they have the knowledge and ability to photograph in any situation, using any and all light sources - including the Fireworks show that will happen during your reception. Photographer C is your best choice as you can trust that no matter what they will capture the moments that count because of their ability to work in any lighting situation. While photographer B only displays proficiency in indoor and night situations, they are still a viable second option as their skills are fairly suited for your needs.
Once you've narrowed down the able candidates, all that's left is determining which photographer you get along with best, which photographer's style you love most and who fits your budget and provides the products you are looking for.
Hiring the right photographer is a pertinent part of being satisfied and getting the quality images you deserve.