...write a speech?
...practice a speech?
...get the audience's attention?
I get these kinds of questions on a regular basis. It reminds me of all the crazy diets people go on in order to lose weight fast and with no effort. What's the "best" way to lose ten pounds in a week?
No one can tell you what's best for you. There are a lot of methods, techniques and strategies out there, used by speakers from the beginning of time. I've given many suggestions on this blog, and I'm sure I've suggested the best way to do something plenty of times.
But you have to figure out for yourself, through trial and error, what's truly best for you and your audiences.
Copying what others have done, without any analysis or evaluation, may not get you the results you're looking for. Assuming that one way is "best" without trying another way is limiting, and doesn't allow you to fully develop your own style as a speaker. Just because Zig Ziglar or Tony Robbins uses certain techniques, it doesn't mean those techniques will work for you.
So take the suggestions from the experts and try them to see what works best for you, your personality, your presentation style, and your particular audiences. Don't take my word for it that one method is best. Do your own evaluation and find out for yourself.