1) to get better at selling, one of the first things to do is more practice [1] at selling.
2) there are some skills to learn, and these skills are "soft" ones - which typically receive disdain in techie culture [2].
Last year, I ran for public office. I discovered to my surprise that I interviewed [3] poorly. This explains why I've had difficulty getting hired in the past. I plan to join Toastmasters later this year (when my schedule opens up) to help correct this.
Some books:
Outfoxing the small business owner. Cynical, salesman oriented book. Decent insight into the psychology of many small business owners. http://www.amazon.com/Outfoxing-Small-Business-Owner-Relatio...
E-Myth revisited. We all have cultural baggage about what a business is, and isn't. And for many businesses, that baggage gets in the way of actually getting work done, or getting ahead as a business. http://www.amazon.com/E-Myth-Revisited-Small-Businesses-Abou...
Notes:
1 - If you've got a good feedback loop for yourself, then any practice, good or bad, will help (aka: practice makes perfect). If your feedback loop tends to the same sort of self deception that most people have, then I recommend finding a coach (aka: repetition will cement bad practices, only perfect practice makes perfect).
2 - translation: "dude, you're turning into a SUIT!" (with audible disdaining tone used for last word).
3 - While interviewing for a job, and interviewing in the media share the same name, they're different enough that books aimed at helping one tangentially help the other. But at least I now have a brilliant retort to "what is your greatest weakness?" A: I found that I interview poorly.
http://www.gitomer.com/
You might find this helpful too:
http://www.amazon.com/Outfoxing-Small-Business-Owner-Relatio...