These are great books for starting off with the why and how of sales:

Daniel Pink - To Sell Is Human: The Surprising Truth About Moving Others http://www.amazon.com/Sell-Human-Surprising-Moving-Others/dp...

Dale Carnegie - How to Win Friends & Influence People http://www.amazon.com/How-Win-Friends-Influence-People/dp/06...

As you understand the macro details of sales, the more micro things (tactics, strategies, best practices) are probably best served by specific industry or specific aspects of sales. For example:

http://www.amazon.com/Behind-Cloud-Salesforce-com-Billion-Do...

http://www.amazon.com/Sales-Acceleration-Formula-Technology-...

http://www.amazon.com/Predictable-Revenue-Business-Practices...

I also really like Jason Lemkin and his SaaStr blog: http://www.saastr.com/ Loads of SaaS sales practices on there.

Behind the Cloud by Marc Benioff http://www.amazon.com/Behind-Cloud-Salesforce-com-Billion-Do...