Dont get me wrong I am not saying not to think up things to talk about before the date or encounter I just feel to build actual rapport with someone those subjects will have to fit the person your talking with and will be different in every situation.
One thing for nervous people to really reprogram in there thinking is that a person of interest is different then anyone else you talk to on a daily basis. When you separate them from your everyday people that fear that they are somehow different and will think your stupid is what brings on nervousness. This is not to say I dont get nervous. Sure I am just like everyone else but I have learned to talk my self out of the fear and just do it.
I posted some coaching lessons for some members somewhere here in the forum with a step by step guide on how to start a convo with anyone and lead it anywhere. The same concept applies to dates really. On dates you can go more in depth though.
There are a couple more examples around where I dont talk about donuts but I cant find them (snort)
So hopefully you observed the person your about to go on a date with or strike up a convo with for a few minutes. Even on blind dates you can pump the person who set you up for some info. Then take note of a few of those things. Learn to pick up on keywords they use that can give you more subject matter to talk about.