The key to flying with your dog is preparation. If you are flying internationally, make sure you know the quarantine requirements of the destination country. It can be as much as 6 months which is a lot longer than most people have for their vacations!
Cabin or Hold?
If you have a very small dog you may be able to take him in the cabin as long as the crate is approved by the airline and the size of a piece of carry-on luggage.
Most dogs however, will need to travel in a crate in the cargo-hold. Airlines require a crate that's big enough for your dog to stand up and turn around in, check with the airline about the required dimensions.
In order to ensure that your dog is able to travel with you, be sure to inquire about the airline's policy before you book tickets. Some may not transport dogs at certain times of the year or even certain times of the day.
Make sure he goes before you go
Before you fly it is important that your dog has had a good walk and that he has gone potty. Line his crate with shredded newspaper because it is very likely that he will urinate while in transit even if he doesn't do this normally. Flying can be a scary experience and a dog will often lose control out of fear.
Food and drink
There's some debate as to whether it's a good idea to put food and water in the crate. On one hand, it seems sensible because he might get thirsty or hungry, especially if there are delays. On the other, it may spill and make a mess in the crate.
It might increase the chances of him having to go potty and the combination of stress and food could also bring on an upset stomach.
A dog can go several hours without food and water, but if in doubt, ask your vet what he or she recommends and ask the airline what their policies are.
If you are providing water, consider freezing it before you leave. This will make it less likely to spill while the crate is being loaded.
Make sure your crate is clearly marked on the outside. Put reflector tape on it to make is easier for identification and be sure to have your details and your dog's name tagged to the crate. Believe it or not, it's also a good idea to label which way is up!
Include care instructions with the crate in case of long delays. Check with your airline on whether they will allow you to watch your dog being loaded. Some airlines may give you a note to let you know once he is on board.
If you have a connecting flight, find out if there's the option of taking your dog for a quick potty break.