So in conversation I can be akward of course, aren't we all? I try to go by this rule of thumb "When in doubt, emulate". Don't get me wrong here, I don't mean become a social parrot but try and mirror everyone's demeanor and general "vibe" in a way that feels natural if that makes sense.
During conversation you can also try restating the last part of what they said in a slow deliberate manner, this makes you seem thoughtful and calm. It also provides you with a mental buffer to figure out a response.
Remember though, its all in the execution