Unlike most philosophy, Korzybsk gives us lots of real methods and practices to improve our thinking. He lays out in great detail the errors we have inherited from earlier systems and how we can overcome them. Korzybski's work has probably been a significant part of the inspiration behind several later self-help systems.
This online book was produced by scanning and OCRing, a sadly imperfect process, so please excuse the few errors and weirdnesses. If you don't mind pdf, I noticed that recently, The European Society for General Semanics have improved their online version of this book, and now have a searchable text pdf version to replace their earlier image pdf version, you can find it HERE Rod May 2007