75 coloring books perfect for adults! I love the architecture books especially, but the fantasy and fashion coloring books would be great for practicing shading. I usually use colored pencils or Staedtler pens.
Booktopia has Color Me Happy, A Zen Colouring Book : 100 Coloring Templates That Will Make You Smile by Lacy Mucklow. Buy a discounted Paperback of Color Me Happy online from Australia's leading online bookstore.