Tell the photographer what style of photos you like. A lot of the way photos are taken now a days are edited with filters to make them look a certain way and have a certain feel. Although the camera placement and lighting still needs to be a certain way, if their is a certain type of photo you’re looking for, show him examples ahead of time.
Build a connection with your photographer. While on that topic, make sure the person you meet with will be photographing at your wedding. Make sure that it is not his assistant of someone in his company. A heavy portion of your wedding day will be with your photographer. Its a lot more comfortable and natural to take photos if your photographer isn’t a stranger you just met, but someone who you have met before and are comfortable around.
Make sure to strike up a contract with your new found photographer. Be sure to outline details like pricing and payment, what happens should he not be able to attend and resolutions for other problems that may arise. Also be sure to find out his or her over time policy should you run later then expected on your big day. If he works by hour or by day is another key point too.
Be sure to portray who the key players are at your wedding. Although getting some sort of shot of everyone is great at every wedding, especially if you intend on sharing all these photos on facebook, or socially for all to see. Be sure to inform your camera man as to who the best man and woman are, grandparents, really close friends and extended relatives. That way he can make a point of getting great shots of them, as you share a special bond with them!