The US Tennis Association has developed a chart of guidelines for parents entitled "Parenting My Champion: Developing Talent." The chart shows three stages of development: Introduction/Foundation (ages 5-10), Refinement/Transitional (ages 10-14), and Elite Performance (15 and over). At each stage the USTA gives recommendations for things parents can do to encourage the child, keep things in perspective AND foster long term development and success.
Parenting My Champion: Developing Talent (Used with permission of USTA)
Many more documents for parents can be found in the Successful Sport Parenting CD.