Please note that the images are copyright protected and can only be used for educational and training purposes. If you want to use your drawings commercially, you have to work from your own photos or get permission from the artist. Search out your own subject matter from real life wherever possible. Use an A4 sketchbook and always jot down the date of your drawing and take notes.
Do each task regardless of agreeing with the subject, this will teach you to push through problems. Or if you have already something planned to use as a motif that suits you, the better. Never be overwhelmed by a subject that seems far too intricate for 10 minutes, the images are just indicative, so do what you can and leave the drawing unfinished and whenever you feel like it go back to it.
A small amount of images of the following books have been used, which I recommend as the best source for this drawing challenge. You can order most of them Online. If you want to buy only one book, I advice to get "The Art of Basic Drawing" by William F. Powell.
William F. Powell - The Art of Basic Drawing, Walter Foster (Publisher)
Arthur Guptill - Sketching and Rendering in Pencil
Andrew Loomis - Successful Drawing
J.D. Harding - On Drawing Trees and Nature: A Classic Victorian Manual
Joe Weatherly - The Weatherly Guide to Drawing Animals