Second this - it's an incredible resource and I have seen many people go through this book go from zero to competent. My old private art instructor 100% openly admitted to her classes being heavily influenced by the book to the point she considered it "required reading". Betty Edwards' methodology works!

Once I got to college I took two drawing courses at two separate institutions. They both ended up being a total "class-version" rip-off of the book. We progressed through the exercises in the exact same order. It makes me incredibly unhappy that my college professors didn't credit Betty Edwards like my private art instructor did.