1. I tell them to define why they want to homeschool.There is a multitude of reasons why any one family begins homeschooling but there is usually one main reason. For us it was a better tailored education. For some it may be religious reasons, and yet others may only want to keep their family closer. Once you've decided why homeschooling appeals to you, you can move on.
2. I next recommend Cathy Duffy's book 100 Top Picks for Homeschool Curriculum.This book lists lots of material and does a good job at explaining their methods. This usually helps the person decide what style of teaching they want to start with. I let them know we use TWTM classical approach in case they want to discuss that in more detail later.
3. I tell them that they should take it slowly.
The best advice I ever received was that you will not harm you kids in one year. If you don't teach one thing that first year, they will still progress because they are growing children and that is just what they do!
4. After that, consider the details.Other things I mention, if their head isn't spinning by this point, is to consider a curriculum fair, know their legal rights, and start learning the lingo. Study the vendors and speakers of a curriculum fair before setting foot in one. The first time homeschooler can become completely overwhelmed at one of those. I tell them to get a copy of their state's homeschooling law and READ it. It may appear incomprehensible, but every homeschooler should know their rights. And lastly I give them a few code words that will help them separate the creation based curriculum from the rest. No matter which side of the debate you are on, you should know what to look for.