A: Keep it short and sweet!
Here is an example:
Dear Mr. X,
My son, Brandon is 11 years old and loves acting, singing and dancing. He has appeared in numerous local productions, and we believe he is now ready for more professional work.
We live outside of New York City and are willing to travel in for auditions.
We would love an opportunity to meet with you at your convenience.
Please feel free to contact me by email at sallysimon.org or phone me at 345-555-5555.
Thank you for your consideration.
Sandra Dee (mother of Brandon)