I need to get used to the British way of responding with "No" when they really agree with you.
For example, in response to "The weather's not looking good," I would say "Yeah." The British say "No." (No, it isn't.)
It's a bit jarring -- feels like they're disagreeing. For instance,
"London isn't expensive."
"No." (what? you're saying it's expensive?)
"I don't have a ticket."
"No." (what? you're telling me I
have a ticket?)
"There's not enough room."
"No."
etc. Quite disorienting. I guess it's also a little more hard work. You have to keep track of when to say "Yes" and when to say "No".