Best way to choose ingredients/products is by hair properties (it will also help people to give you advice.) Here's a link to help you with yours Live Curly Live Free - Curly Hair Basics Once you determine your properties, you can look for others with hair like yours and see what they use. It's the best place to start.
Personally, I didn't find the CG book all that useful. The e-book available on the above site has all the information in one place. The DVD with the CG book is really worthwhile. It shows you how to style your hair. I could never use the copious amounts of products they use.
Some people get away with using drugstore products. My hair prefers the more natural products from the online, boutique type companies. I stay away from chemicals, especially polyquats. Use jelly type products instead of the gels because of that. My stylist says to stay away from mousse. Even if it doesn't have the drying alcohols, the propellant can be drying.