I've found that (for me, at least) situations are never as bad as I expect them to be. This plays out over and over. I always thoroughly remind myself of this after I get of the situation, and I remind myself the next time I'm nervous about something. I never seem to believe myself.
I'll rehearse the words I want to say in the situation over and over in my head. I'll imagine how I'll be standing and what expression will be on my face. Yet, I get into the situation and don't use any of the words (or anything similar), everything goes by the wayside...and it still comes out okay.
I don't know if I'm incredibly lucky or if I just have an exceptionally overactive (and negative!) imagination. Either way, I will keep on reminding myself that that interview or that conversation I need to have or even that flu shot won't be as bad as I'm expecting.
Maybe one day it will stick.
How do you approach situations that make you nervous? Do you have things that you do to help make it better?