Keeping your voice calm, soothing, and upbeat will go a long way to helping him relax. Here are other ways to make doctor visits run a bit smoother:
Time it right. Try to schedule appointments early in the day when the doctor is less likely to be running behind schedule. Aim to arrive well before the morning nap or right after -- so your baby is rested and fed.
Divert his attention. Bring your child's favorite toys and books, and a light snack to keep him occupied if you face a long wait.
Play doctor. While your tot is still too young to understand a toy doctor's kit, playing with it may help familiarize him with the tools. You can also perform a mini exam on one of his stuffed animals at home to prepare him.