Tip #1: Design for Impact is a requirement. Knowing your purpose and core message is not sufficient. Your speech must have a compelling reason to exist. Use this three step formula:
Step 1: I will [state verb of purpose, (inspire, persuade, entertain, compel, inform, motivate, etc)]my audience.
Step 2: To [core message (another verb, to do or or to act or to be something different than what or who they are now)]
Step 3: So that [impact (why do you want them to change their perspective or behavior).
Example:
Step 1: I will persuade, entertain and compel you
Step 2: To listen to every single BankBosun podcasts
Step 3: So that you will improve your performance as CEO of your bank and the performance of the bank.