i did have this problem as well. i think at the end of the day it comes down to your conversational skills mainly, and something i got told to do by a friend was to listen to the radio pick out one word at random from what the DJ was saying (example Weather, news, holiday, etc) and then start talking to yourself and try and make the one word become a whole conversation. So from one word becomes a whole conversation, the more I did this the better I was able to talk freely without feeling limited.

If you can generate an interesting conversation from anyword, you shouldn't ever have a problem!

atb

Adz