I recently attended a conference where one of my classmates was a pro tennis coach. Mark and I would like to get River into tennis, though whether or not he wants to go pro will be based on his interest and ability. Here are the recommendations the coach gave me for setting a solid basis for a youngster:
Age 7 -12 months: Buy some ping-pong balls and roll them back and forth with baby. This helps develop tracking skills.
Age 3-4: Buy a racket and let the child hit against the garage or other wall.
Age 5 or 6: Take the child with you when you go play tennis. See if expresses any interest. Wait for him to ask for lessons.
Age 6 and up: When child asks for lessons, provide them. This coach recommended private lessons of only 15 minutes since she says that is only as long as most kids can concentrate. She suggested finding another family/child to share a half-hour or hour lesson with, dividing the time between the two children. She recommended a coach who is firm about expectations and behaviors.