Ashbad, I read that book back when I was around 15 or 16. The presentation is dry but that's a good thing. It keeps the content clear. As I recall the book has suggestions for additional exercises, or if it doesn't, it's not hard at all to think up some similar projects on your own.
As to specific practice, just draw stuff. Drawing from life is always good, thou a little uncomfortable at times. Every now and then I'll pick up a magazine like national geographic or a fashion magazine and draw animals or people. Go to imgur and draw random stuff.