I get nervous still sometimes. I was a high school teacher for 4 years out of college and I did some adult training... which is similiar but alot easier because it is an interactive situation and you loosen up once you learn your crowd... But on occasion I have had to give a speach or do a reading (church services) and for those I would still get the jitters...
#1 if you take a beta-blocker that will make you calmer... and not get the jitters as bad... concert pianists and orchestra folks take them... they are on the banned substance list for archery and other aiming type events in the olympics... BUT I wouldn't recomend it... (I take them for blood pressure)...
#2 ok you have heard take a deep breath before beginning... well do that because the 1 thing that can really get you is shallow breathing... you take a tiny breath... say 2 words... take another tiny breath say 2 words... and just don't relax enough to really breath in enough to say more than 2 words at a time... it can be exhausting... So take a good breath... try to speak just a bit more slowly than you feel like you want to... and repeat the same breath... and speaking... It really helps...
the last time I had to give a reading was at a funeral and it was very stressfull because I didn't want to loose it up there reading in front of everyone... my hands were shaking so bad I could hardly read the sheet I was reading from but focusing on my breathing and regulating the speed I was talking.
Another thing that has helped me in the past is if you can memorize part of what you are going to say.. (if you are reading)... not the first 2 or 3 sentences... the ones right after that... when you reach the peak of your nervousness...
Another is a planned pause... "today I am here to tell you about the benifits of eating an apple every day." pause (everybody expects a pause there... hold it for an extra second and take your slow breath in...
Don't think! Don't think about your audience... think about what you are doing... what you are saying...
OK and my number 1 suggestion... Know you will get nervervous and accept it and practice dealing with it...
Believe it or not throwing competitive darts has helped my ability to deal with being nervous and public speaking. Learning to overcome your nervousness and tenseness to throw the game winning bullzeye... on command helped me learn to relax in other settings...
Practice this... like you are watching your favorite team and it is a critical time in the game... you feel your muscles tightening up ... try to relax... take a deep breath and try to live the moment... outside the moment... like you are in a "zen" state... or take up darts and play people for money to practice relaxing in pressure situations...
Good luck...