One of the best tools I ever learned was mind-mapping. Years ago I picked up a book by Tony Buzan and read about mind-mapping. I've used it in my corporate life, while studying and continue to use it in my own business.
I mainly use if for notes during workshops and seminars - it's much easier to create one or more mind maps than have pages of hand-written notes.
Ideally use as large a sheet of paper as possible on which to create your mind maps. However, I often use an A5 notebook and a series of coloured pens (if I have them with me).
I prefer to create mine by hand but there are several mind-mapping software applications out there now.
Pick up a copy of The Mind Map Book today and learn the simple techniques to create your own mind maps. There's also a Mind Maps For Business.