I can't hold a conversation is it normal?

I'm shy and I always have been. I find it hard to talk to people unless I'm comfortable or know them well, but tonight I'm going out with my sister and her work mates, so I'm worried because I won't know what to say, so is it okay just to ask them how they are and wait until they speak to me? I'm self conscious because I don't say much and I start worrying how I come across to other people. I get nervous and clammy. And it's not a nice feeling :(