Being real with people is the most effective way of gaining their trust. If they spot a fake, you've lost all hope and it's time to move along to another mark. A fake interest is something like "oh neat" or "that sounds cool" (it's ok to say these types of things but don't repeat them over and over). It's always important to interject with relativity "so that's kind of like..." or "that reminds me of..." "is that related to..." things like this, making associations, connecting ideas. This keeps the conversation going. Never say "that's weird" "I've never heard of that before" or anything that potentially shut down the flow of...