Okay, so you're in highschool and you want to homeschool (or a parent of a kid in highschool)? Well the first step is always RESEARCH! Make sure you know what it's all about, make sure you talk to people who know what they're talking about, and make sure you're sure that this is going to work for you (but then again, why wouldn't it?)

There are a couple books that I definately recommend! The first is:
The Teenage Liberation Handbook: How to Quit School and get a Real Life and Education
and...
Real Lives: Eleven Teenagers Who Don't go to School

Read up on your state's law a little bit! What are your states requirments, and how does the whole procedure work?

Research on the internet for webpages about homeschool, there are plenty.

Make a list of objectives. Need a guideline? Here are my objectives.

Meet with your school counselor. Discuss the whole thing, why you want to do it, what it will mean for your future, pros and cons, etc.

Meet with the director of curriculum in your school. He/she can help you with the state law on homeschooling, and explain everything to you.

Meet with other people experienced with homeschool. Talk to whoever you can! Just make sure they know what they're talking about so you don't pick up any false information.