Excellent little books. I bought this and Improving the Rider's Position at the same time. They are superb. Only 24 pages in each but packed with easy to read tips on how to improve your riding. The illustrations are great showing the correct and incorrect aids, the how and the why in different moves. As a beginner I found these invaluable and for example, noticed how my horse reacted to voice exactly as described in the book.
As you progress and learn more difficult things, it's easy to let the initial things slip (there is so much to remember), so it is great to just pick up this book and read a couple of pages, say on holding the reins correctly, or leg position, just to remind yourself of the basics.
Recommended for all ages.