For me, it helps to slowly pace around a room and if I get stuck I just try to match my speaking rhythm to the "beat" of walking. Sometimes, if I know more or less what I'll be saying, I write down bullet points of what I need to or should say. If I get stuck I slowly read the word or phrase that I'm stuck on. If the word or phrase isn't written down it sometimes helps me if I spell out the word as I say it. Just some tips that help me, maybe they can help you! Good luck!