Since every piece of RT comes from cap 413, all the responses can pretty much be expected.
Try writing a flow diagram of your initial calls and the possible come backs...
"standby"
"squawk..."
"remain clear of controlled airspace"
and so on.
Then hand it to a friend and get them to do the other side of the conversation. It's how I polished up my initial calls for a service, and anything else is just a formality. They don't even have to be a pilot, they just read what you've already written out.