Reddit reviews Brain Magick: Exercises in Meta-Magick and Invocation

I'm not sure about essential to every occult library (and I realize some of these aren't necessarily considered primarily 'occult' texts), but here are a few I've found useful:

• The Golden Dawn - Israel Regardie
  
• Morals and Dogma - Alfred Pike
  
• Modern Magick - Donald Michael Kraig
  
• The Secret Teachings of All Ages - Manly P. Hall
  
• Initiation into Hermetics - Franz Bardon
  
• Sefer Yetzirah - Aryeh Kaplan
  
• The Secret Doctrine - Madame Blavatsky
  
• Liber Null & Psychonaut - Peter J. Carroll
  
• The Book of Thoth - Aleister Crowley
  
• Undoing Yourself with Energized Meditation and Other Devices - Christopher S. Hyatt
  
• Prometheus Rising - Robert Anton Wilson
  
• Enochian Vision Magick - Lon Milo DuQuette
  
• The Chicken Qabalah - Lon Milo DuQuette
  
• Brain Magick - Philip Farber
  
• Info-Psychology - Timothy Leary
  
• Beelzebub's Tales to his Grandson - George Gurdjieff
  
• Initiation, Human and Solar - Alice Bailey
  
• The Red Book - Carl Jung
  
• Principia Discordia - Malaclypse the Younger

I recommend you to grab a copy of Brain Magick which will give you a scientific approach to magic experiments. I highly recommend this book to any practionner whatever their approaches or Paths.