Train your pet for traveling
Help your pet love their carrier. If the carrier is a comfortable, happy place and not a new, weird place, life is going to be a lot easier for them and for you. So what you need to do is to get your carrier ahead of time and create happy associations to it. First, make the proper introductions: if you seem very happy about the new carrier, your pet will feel the same. Also give them some treats inside the carrier, play with them nearby, put their favorite toys in there or whatever makes your pet very very happy, needs to be associated with the carrier.
Acclimation. Slowly start putting your pet in the carrier for extended periods of time. Do it gradually – so maybe the first time you'll only do it for ten minutes, then for half an hour and so on. It's very important for them to know that they will be let out from there at some point. Also, stay near while they are in the carrier – for example, when you're at your desk or watching TV.
Recreation. We should recreate what a plane ride would be like. You can put the carrier on the floor of your car as you're driving so that would imitate the vibrations of the plane so it won't be such a huge surprise for your pet and they wouldn't get scared.
Train your dog to use wee-wee pads, as it won't have access to do it's needs during the flight. It must know that wherever it sees a pad, it's allowed to pee. This is also very useful for hotel rooms or any other places where there is no access to a 'dog toilet'.