The speaker and author Byron Katie has a great, brassy line about meeting new people: "When I walk into a room, I know that everyone in it loves me. I just don't expect them to realize it yet."
When you're starting a conversation with that new co-lead or with the gal at the networking event, "do it in more or less the same manner as if you were going up to someone you already know and are friendly with," says SucceedSocially.com.
You're not assuming BFF-levels of closeness here, of course. But going in with genuine warmth and openness builds the first layer of trust. It helps your conversation partner be at ease, and it also gives you more confidence.