When speaking to a group, your most important words are the very FIRST words you speak.  Here is a good opening template to follow:

1.  Grab them by saying,  “I am here for one reason and one reason only:  to (get more money into your bank account; to empower you to raise your child’s self-esteem; to set you free of pain, guilt and fear; etc…depending on the what focus of your talk is).

Then say, “Can I get a big thumb’s up (or Amen!) to that?”

2.  Then, briefly mention your credentials (very briefly!):  “I’ve built my business to x-levelby using these same strategies!” or “I’ve worked with 12,000 kids over the last 20 years!”

3.  Then, say, “Let me tell you a little story…” (here you relate a story that makes your point for you:  “Let me tell you about what happened to a friend of mind named Carl Taylor…)

Note:  At all costs, avoid starting your presentation by saying “I’d like to thank the committee for having me…(and the event organizer, and my old professors, and the chairman…etc?)  and “Can you hear me in the back of the room?”