There was an older potter being interviewed on PBS. He said that the secret to making artistic pottery was to make 20-30,000 pots and it would come naturally.
In a similar vein a car stopped in New York the driver asked a man walking on the side walk, "How do I get to Carnegie Hall". The man replied, "Practice, practice".
There is a group called Toastmasters that exists primarily for giving people experience in public speaking. You may want to find a local group and see what would be involved in getting as much experience as you can.