Sketching and design
This month Coroflot has an article on designers and sketching called Questioning the Cult of the Sketch. .
As someone who has been in the design business for longer than i care to admit here, I can say sketching is an invaluable tool, hand lettering and photography are also excellent are also invaluable skills.
Lots of paper, some good pencils and pens and a fast scanner are necessary.