I have to write an outline of what I'm going to talk about or else I sit in there like a deer in the headlights for the better part of an hour. From past experience I know that I cannot trust my brain to improvise. The "so what do you want to talk about/was there anything else you wanted to talk about" line is the bitter enemy.

I write three to four topics on a piece of paper and let the natural flow of conversation determine which things we do or do not talk about.