Talk to your child before going to the doctor's office and explain why you are going and what will likely happen. If you are not sure what will happen it is better to simply tell the child that you aren't sure, but you will be there with them. Never communicate your fear of doctors, needles, nurses or hospitals to your child.
Encourage your child to play and interact with other children in the waiting room. This will help the child feel more comfortable and relaxed as well as making the visit more positive in nature. Usually the doctor will also have a sticker, treat or toy for the child that will also help reinforce the positive.