I have a lot of familiarity speaking in front of crowds because I used to be a High School Presenter. My day would consist of speaking to numerous teenage classrooms. I never had a fear of public speaking but the butterflys were always apparent right before I got the first sentence out. It is true, the more knowledge you have on the topic the more comfortable you are sharing it with others. The more presentations I did the more speaking became second nature. The butterflies will diminish after time and the possibility of excitement might surprise you.