Over the years I've done a lot of sales (staffing/recruiting, consulting, application development, websites, etc.).  Of course, most 'traditionally trained' sales people would now say, "Everything is sales" or "Everyone is in sales" but I digress. 

There are a few books I've thought are the best.  The first two by Heiman/Miller are 

The New Conceptual Selling: The Most Effective and Proven Method for Sales Planning

The New Strategic Selling: The Unique Sales System Proven Successful by the World's Best Companies

I have a document you can download (Conceptual & Strategic Selling notes WORD document ) that provides an overview with notes on these two books.  The document includes things like:

6 Keys Elements to Sales (Analytical Tools)

1. Buying Influences

2. Red Flags/Strengths 

3. The Buyers Perception of Reality 

4. Win/Results 

5. Ideal Customer Profile 

6. Sales Funnel 

3 Phases of a Sales Call

The Essential Sales Tasks 

5 Types of Questions during the Sales Call  

Another book I stumbled on recently is CustomerCentric Selling which I'm reading now.