Any fool can gain knowledge, and lots of it, but wisdom is something special.
In this day and age when one's word is all too often valued by how many graduate degrees they have, how "well-read" they are, or how many prominent figures they can quote, it's especially vital to know the difference between knowledge and wisdom. Knowledge - information - can be bought and sold. Wisdom cannot. True wisdom comes from the spirit, from experience, from living.
You can't become wise by sitting in your armchair reading books. Workshops and classrooms and lectures and television shows won't give you wisdom. You'll need to live a little, to experience the sights and sounds and scents of the world, take life as it comes, live on the edge (of course, the usual rules of "harm none" and "don't do anything stupid" still apply).
Shamanism comes from the heart and the spirit, not the empty intellect. A weekend workshop or one of the many DIY shamanism handbooks can point you in the right direction, but you must still walk the path yourself - not just read about it. No one ever became a great medicine woman by reading the complete works of Castaneda (or Harner, or Starhawk...)
The Book of Shadows and the shamanic journal are a fairly recent addition; the average nomad shaman or country witch probably wasn't literate. Their "handbook" would be nature all around them, and the spirits who came to them in dreams.