The 22 Immutable Laws of Marketing and Positioning are perfect business books. Both are short, easy to read, and packed with valuable lessons. I often come back to both of them, especially 22 Laws, to make sure I don't forget their lessons.
Positioning is the intersection of product and marketing. Without the correct positioning, your product won't be as strong and your marketing won't be as effective. Choosing and communicating the right market position unlocks everything else.
Here are some of the most valuable lessons I've learned on the subject.
The Target is Not the Market: Your target (whom you advertise to) and your market (who buys the thing) are not the same.
The Shopping List Test: A simple test for whether your brand name means anything to customers.
More This, Less That: A simple framework for positioning from Basecamp.
Optimal Newness: Your customers don't want anything too new. Build the most advanced, yet acceptable, version of your idea.