Oh man, you should have seen me at my first hall cosplay. I was shaking and when I spoke my voice shook... Oy. And I'm a teacher! I teach everyday. I'm up on my little teacher podium everyday telling people what to do, and I freaking break in the matter of seconds when it come to being judged by others. I just don't get it...
Anyways, my 2nd time I was still shaking but it was much much less... and I just kinda prattled on and then turned it over to my partner. I gotta say, having pointed questions instead of the broad, "how did you blah blah blah" helped a lot more. The judges asked about the wigs first, so that made things so much easier for me. I had reference pictures the first time, but they were being passed around. The 2nd time they were at a table, so I could point out certain things about them. The judges did not all sit, two of them got up and looked at our costumes. I was still talking and what not... I really can't tell you what happened the whole time as I don't remember it all. When I'm stressed or nervous, moments tend to blend all together.
Capsulecorp had a good suggestion of the note cards. You can't guarantee that the judges are going to ask you specific questions, then having bullet points to keep you on target will keep the conversation flowing and on point. I knew once my partner and I were talking about how my cat was so helpful in the construction of the kimono I knew we ran out of things to say to the judges ^^;;