Anything in the Dilbert family of fine reading (smile). Seriously...."Relationship Selling" by Jim Cathcart is a very good book. Easy to read and follow. Good overall explanation of the selling cycle. Good FUNDAMENTALS (smile). And some cool stuff on dealing with different personality styles. Enjoy!
Craig
One of the best books I had read and In fact implemented three quarters of the book was "How To Master The Art Of Selling" by Tom Hopkins.
Among the others that our friends here have suggested.
Wishing you all the luck. Remember, Never give up and every rejection adds to the dollar value of your final sale. 
Dale Carnegie`s "How to Win Friends and Influence People" is certainly worth reading.
I agree that SPIN and Solutions Selling are both excellent and worth investing in either books and/or formal training.
Jeffrey Gitomer`s Little Red Book of Selling. www.buygitomer.com
Kevin Hogan`s Persuasion books. www.kevinhogan.com
Dale Carniegie is beyond comparison. The definitive book of selling.
I am not an affiliate for any of these, they have helped me. But I am a `natural born` saleswoman. They tweaked me....