Start by doing nothing. Most parents who switch to homeschooling will tell you that their student needed time to "decompress" after being in the public school system. The rule of thumb is 1 month for every year they were in the system. Use this time to read good books together.
Read some good books yourself. Start with "The Unofficial Guide to Home Schooling" by Kathy Ishizuka, which is a great book for getting all the basics. Another book for answering the questions of friends and family is "So--Why Do You Homeschool?" by Mimi Davis.
Know the homeschooling law in your state. If you are approached by your local school district, you will be armed with the truth of the law and will be able to refute them if needed. Not all school districts are antagonistic toward homeschoolers, but some are. Remind them that homeschooling is legal in every state.
Explore interests that might have been hidden by the public school setting. The basic academics are accomplished in about half the time it takes in the public school, and some can be integrated directly into the student's interests. For example, if your student likes music, you can combine a music lesson with a science lesson by studying sound waves.
Search out other homeschooling families. It's imperative you have a support system, and it's nice to have other children with which your homeschooled student can socialize. Go to the National Home Education Network website and search for local groups in your area. Click on the "Networking" tab and then select "Support Group Listings."
Join the "Homeschooler's Notebook," a free biweekly newsletter, by sending a blank email to [email protected]. Here you will get encouragement and advice from experienced homeschoolers, and you can even join their Yahoo! group and post your own questions about homeschooling.