Some may say this book is the ultimate unschooling guide: http://www.amazon.com/The-Teenage-Liberation-Handbook-Education/dp/0962959170, by Grace Llewellyn. Other resources include http://www.freechild.org/unschooling.htm

Parents choosing an unschooled approach to their child's education may wish to keep accurate records of lessons and activities, extracurriculars and roles (especially active participant and leadership roles). A supporting portfolio may also be helpful.

When considering application to high schools or colleges, there are books such as http://www.amazon.com/What-Schools-Other-Parents-toKnow/dp/0452289521, and http://www.amazon.com/What-Colleges-Dont-Other-Parents/dp/0452288541 offering advice on essays and "packaging".