You only have one chance to capture the special moments and occassions in your life, so make sure you place someone in charge of taking photographs, and possibly video. Don't let these special moments go unrecorded.
Hiring a professional photographer for your wedding or special event will guarantee you have quality photos from your day. A trusted friend or relative, who is well trained in the use of their camera and scene set up is also an option.
Be certain to give the photographer a list of specific poses and group pictures that you desire. You will be busy the day of the event, and won't remember what you want - so it's important to have your photographer keep to the list. There are no Do Overs.