Consider this idea:

• How is public speaking different to giving a speech to an empty room, (or other similar but not stressful event). For bonus points actually do the non-stressful thing and afterwards consider what might be different.
• Make a list of as many of the parts that you can come up with
• Mitigate the parts that will be a problem for you in any way possible.

In this way a great beast of a "public speaking" problem can be managed to smaller think-able tackle-able tasks.