As an instructor and a user of Adobe products, I am always trying to find more efficient ways of working and navigating Adobe's programs. I have five shortcuts that I use on a daily basis:
Pressing the Control (CTRL) key will turn most any tool into the Move tool
Pressing CTRL + Spacebar will turn most any tool into the Zoom tool
Pressing the Spacebar will turn most any tool into the Hand tool.
CTRL + Z will undo errors (this works in all programs that I know)
CTRL + W will close a file: a document, workbook, presentations, database, Photoshop file, Illustrator file, etc. This works for most files. However, there are exceptions. For example, it doesn't work with Crystal Reports.
Of course, shortcuts are only shortcuts when they become second nature. Until then, practice, practice, practice!