#16 Thinking you need to teach everything yourself.
Since it's called "homeschooling" people often assume that all learning is supposed to happen at home. But "homeschooling" is something of a misnomer-- it doesn't have to happen at home, and parents don't have to be the only teachers. Homeschooling gives you the freedom to find the education that best fits your family-- so if you don't feel comfortable with a subject, or just like the sound of someone else teaching it, outsource it. There are DVD courses, online courses, homeschool coops, tutors, commercial classes... you may even be able to send your child to your local public school for a class or two. Also, include learning that goes on through extracurriculars-- that counts too!