Congratulations on your engagement...
It's that time of year, one knee, sparkly rings, giddy family...Congratulations!
Of course now come the big plans--venue, dresses, cakes, and, well of course, photography. And when it comes to photography, I can offer up at least a few thoughts on the subject.
First and foremost, out of all of the "things" you may want, flowers, cake, food, etc, the photographs are what will last and provide you with a documentation of this important event, the people who were there, and the details of the day.
Photography is a professional service; your guests aren't there to work, they are there to enjoy themselves and your day. Leave the work, whether it be catering, decorating, music, or photography, to the professionals.
An experienced photographer should be able to provide a range of service, from well lit and carefully posed family formals, creative and interesting portraiture, to truly candid documentation of the action and details which fill the bulk of the day.
A photographer who specializes in weddings has the experience to anticipate action and knows what to look for throughout the day without direction, providing comprehensive coverage of the main events as well as the unexpected and behind the scenes vignettes. He or she has the skills to work under pressure and within a strict time frame and still deliver commercial quality portraits as well as documentary coverage, utilizing the necessary range of equipment and lighting to get the job done. A professional also has the skills and experience to handle the often overlooked aspect of post-production of your images, including editing, color correction and retouching, as well as album design.
Finally, finding a photographer who is right for you and your style is as important as any other choices which reflect your personal taste. First and foremost, find a photographer whose work speaks to you. Comparing the specifics of services or packages is meaningless if the work itself doesn't suit your taste or aesthetic. Good photographers are artists with vision, style and passion. So find a photographer whose work you like, and with whom you can work and vice-versa.