[jkingsbery]

A few things come to mind:

1. I agree with the others who said it's a thing you need to practice. While talking to people can be stressful, talking to people about things you're interested in is much less stressful. Find something in common and talk about that.

The connection doesn't need to be done entirely in person. For example, if you and your coworker share an interest in some area (space flight; unit testing; a particular video game; etc.), and you come across an interesting article, write a quick note to that person saying "Hey, saw this, thought you might find it interesting. I like how..." Then when you see that person, there's a good chance they'll say "thanks for sending me the article on Topic X that we both enjoy!" and a relatively low-stress conversation will follow.

2. On the other hand, it helps to set limits. If the sales people you work with tend to be more challenging, see if you can involve your boss, a product manager, or someone like that as a filter. Set-up time on your calendar blocking off meetings. Meet people half way, certainly, but also make it clear what you need to be successful.