I believe I can help you here.
I had a job in sales all of last year and part of this year. In all honesty it helped somewhat, but was the wrong environment to learn to be a better conversationalist. I believe I learned how to give and earn respect mutually in that job, to be polite without being a pushover. I also learned to believe in what I said.
However if you're looking to be a better conversationalist, I'd recommend being in the hospitality industry. More specifically in a restaurant or bar. I work part time behind a bar right now, serving drinks and making guests feel at home. This is a much better job because you're interacting with people in a comfortable environment.
They're at the bar to unwind, have a drink and talk to somebody.
In a sales job(I did cold calls, then went to people's houses), people are interacting with you on a level of politeness and respect, but they're also wondering how you're going to screw them over. They ask, "So... What's the catch?".
It isn't a homely environment and won't teach you how to interact with people on an emotional level. You will learn how to win respect, you will make a FEW friends, and you will break out of your shell in a sales job, but it's a very dry job because both of you have your own agenda and that's your primary goal. In a bar or restaurant, sure you do get percentage of profit, but when Im there my primary goal is to have a good time, and people feel this.
cheers
