You really want to do some good searching and researching. If you like photos of friends or family, ask them who they used.
If no photographers have been recommended to you and you're searching on your own, then there is something important you need to know.
Make sure the pictures you're looking at come from the photographer listed. Let me explain. There are individual photographers and companies with multiple photographers. The companies post the best pictures on their website. If you choose to use a company with multiple photographers, make sure you find out which photographer belongs to which pictures, then make sure you book the photographer you like the most.
Once you have it narrowed down to a few photographers, there are a couple of things to compare to help you make your final decision. The two main things are package options and cost.
These days it seems customary for photographers to offer a variety of packages, especially for weddings; most photographers have a package that includes engagements, bridals, and wedding day coverage.
Once you have looked at all the photographers and their packages, compare the prices and decide which one gives you the best value.
Another thing to keep in mind; how much experience does the photographer have?
And finally, give the photographers a call. Ask them questions and make sure you're getting what you want.
Good luck finding your photographer!
P.S. For my engagements, bridals, wedding, and newborn photos I used Darla Roze Photography. Her work is wonderful and she's great to work with! http://www.rozephotography.com/