What is their history or experiences as a photographer? Someone who got their first 'professional' camera last Christmas doesn't automatically make them a professional. It's important for someone to have taken the time to learn how to properly use their equipment and be able to use it well in a broad range of situations and circumstances. Are they used to photographing people and fast-moving events, or do tend to take landscape photographs? Different skill sets and equipment is required and they need to be able to cope with unexpected situations.
How many weddings have they photographed? This follows on slightly from the first question and gives you an idea of their experience in this very unique and high pressure type of photography. Someone who is just starting out on their own might benefit from assisting a seasoned professional to get an idea of what is involved in photographing a wedding such as timings, details, building confidence and utilising lighting. This is how most wedding photographers begin their career (myself included). A new wedding photographer however is not necessarily a bad thing, especially if their current portfolio shows good portrait work which can easily be applied to a wedding. What you should be a little wary of is if there is no relevant previous work.
Can they show you a couple of full weddings? Either on their website, slideshow or in an album they might have prepared. Make sure you have a look at a few of their past weddings from start to finish if possible, ideally at the same time of year as you are getting married. This will enable you to check the consistency and quality as this needs to be on top form every time. You shouldn't rely just on the 'highlights'.
Do they have a contract you can look at? This is very important as it binds you to the photographer and sets out rules for payment and protocol. Make sure you read the fine print and are happy with everything before you decide to go ahead. Ask the photographer how much the deposit and balance is, and when these are due. If they don't have a contract it may be best to avoid them, as there is little to no legal protection for you covering the service and what you have paid.
What do you receive for the price and what is the expected turnaround time? This will obviously differ from person to person, but if it's not stated on their website what you will receive as part of your package, then ask them. Editing times are a big commitment in the process and can take a while in the peak summer season. Quick turnaround times and high quality rarely go hand in hand, so it may be worth being patient and waiting a little longer to get a more polished end result. It's also worth asking what their travel inclusions are, so you don't get stung with a heft additional cost for getting married too far from where they live.
How will the day go? Again this is down to the experience of the photographer, but as they are often there with you the whole day they are one of the few people who can tell you a rough order of the day, and for most couples who have never been married before (whereas photographers shoot weddings all the time) it's good information to know. The sort of time they are due to arrive, the sequence of events through the day, when the main photography will take place (such as group shots and the 'couples shoot' if desired), the first dance etc and when they are expected to leave in the evening.
What is their style? It may be evident from their website but there are a few main 'styles' of wedding photography. Traditionally it was very directed and posed, with the subjects of the photography usually looking at the camera straight on. This works for some parts of the day well but often it can be distracting or off-putting. Reportage or documentary style is more laid back and unobtrusive, with the photographer letting the action unfold to enable a story to be told with the photographs. They often plan ahead and are always in the right place to take that perfect shot. The results are more natural and the day happens at a better pace, with less holdups for photographs.
What happens if the weather is bad? Or you get ill on the day? Or something happens to your equipment? These are hard questions to answer but often venues will have separate outdoor and indoor areas to move guests to if the weather is bad. A good and creative photographer may even be keen to involve the rain in some really special photographs that no one else will have - if you're keen to do this of course! They may even bring some umbrellas for you to use too. If the photographer happens to be too ill to shoot your wedding they will hopefully have a system in place to get hold of someone else of a similar style to fill in for them, and should take any price difference on the chin if this happens. Minimal disruption to your big day is important! Equipment failures are very rare but sometimes careless use or accidental damage means that data may be lost. Photographers will of course do what they can to salvage the photographs and should have adequate insurance to cover damages. Many photographers starting out often don't have insurance, so ensure your peace of mind is taken care of! Backup equipment is also commonplace, with multiple lenses, cameras, memory cards, flashes etc just in case there are any unforeseen issues.
I hope this has given you an idea of some key questions to ask a photographer you may be meeting with, or are thinking of booking for your wedding.
Informative posts about weddings and related things, as well as general photography stuff.