When you are looking for a photographer there are many questions you need to ask, so I'll put them here and answer them. Many of these cover if something goes wrong, to give you piece of mind.
1. For a wedding most people ask that the photographer is with the bride from the preparation through until the first dance. This means that they will be with the bride more than any other person for the whole day. To get the best photos you need to be comfortable around them and relaxed. If hiccups happen on the day, then you need someone who will help relax you rather than add to any stress. Always meet your photographer face to face.
2. Pick a photographer whose style is what you want. You can gather this from samples and a portfolio, but make sure the photographer actually took them!
3. Decide how much time you want your photographer to attend for. You can use this to lower the price.
4. Many photographers will provide you with pictures on a USB stick. But do think about what you are going to do with them next. Will you look at them once and then get a few printed? You then leave the rest in a dusty drawer never to be seen again? Or do you want an album/photo book? Or something more funky?
5. You can print out photos yourself, but are the images coming from the photographer properly processed? And do you have access to a professional printer? A good image can be made stellar processed later on a computer, but can be degraded by printing it out on a home printer. A professional photographer should use a high level commercial printer to get the best quality long lasting prints. Remember you do get what you pay for!
6. Do some research. Talking with various suppliers and friends you can start to make a short list.
7. Today many people can buy good quality cameras for not a large amount of money and think that they can take good photographs, but this is simply not the case. To get the very best images full of colour and definition demands higher end cameras and lenses and someone who knows how to use it and compose images. Check your photographer has backup equipment just in case there are any faults on the day.