Don't. Don't prepare for a fearful dog any more than you would for any other dog. The world cannot adjust to the dog. The dog will need to adjust to the world...your world. Don't begin treating your dog as a victim. It will only confirm to your dog that there really is something big and bad and awful out there and make them turn even more inward. That is not your goal.
What should your goal be? It should be to help your dog become as much like a normal dog as possible It should be that dog gets to behave and act like a dog, be loved like a dog and able to give love back. You should expect that your dog be happy.
The process of working with a fearful dog begins and ends with establishing trust. A fearful dog needs and wants to believe in someone. You are that someone. You should start establishing the relationship and trust from the moment your dog walks in your door.
Some Do's and Don't's...
DO talk to your dog in a normal tone of voice.
DO talk to your dog even when it appears they are not listening. They are.
DO break everything down into steps small enough that your dog can feel successful.
DO spend time in the same area your dog is in.
DO give your dog as much love and attention as your dog can handle.
DON'T yell at your dog.
DON'T raise your hand to your dog.
DON"T try to force your dog to do what it is not ready for.
DON'T allow your fearful dog to just curl up in a ball and shut out the world.
Give your dog a place that they can go to when the fear is not manageable for them. However, make it a spot that you can block off when you are working with your dog on something specific. A kennel with a soft blanket is perfect. But don't allow them to just stay in the kennel and never come out to see the light of day. Getting the dog out of the kennel can be trying at times. The dog may even growl at you for invading their space. You can attach a leash and gently pull the dog far enough out that you can pick them up. Sometimes that will not work and you may even have to slowly turn the kennel over so the dog is forced to come out. When you have the dog out of the kennel, put the kennel out of the dog's sight for a short time so they are not tempted to rush back in. Try to give the dog as much time as it takes for him to reach a calm state of mind before you let him have his kennel back and retreat. You want him to see that the world is safe, even out of the kennel. You want them to want to come out of the kennel on their own. Take the dog out of the kennel throughout the day and then let them go back in. When the dog is able to come out of the kennel on its own progress has definitely been made!