By being present, though, I don't mean being there physically - only. I mean when you are with someone you are truly there with that person, or that audience, not thinking or worrying about other things. Certainly a powerful communicator isn't thinking about what people think of her, she is focused on her audience.
A powerful communicator thinks about why her audience should care about her topic. Actually if you are crystal clear about the why, everything else related to your message with flow naturally. This aspect also keeps you from talking about things that really aren't relevant for your audience.
Powerful communicators don't always use slideware (like Power Point) just because everyone else does.
Powerful communicators value their time and energy, and yours. Realizing, even though you've always known this, but really getting the fact that your energy is not infinite and that your management of your energy determines how much you'll have.
One way I've responded to realizing how important it is for me to manage my own energy is choosing not to shop a W--mart. I have nothing against that store and for many years I did most of my shopping there. Today I find I use less energy on shopping (low priority) by shopping in stores that are smaller and closer to my home.
Powerful communicators invest in themselves for two reasons. 1) Investing in yourself ALWAYS pays off and 2) It's the fastest way to get better.
Powerful communicators commit to excellence. That's why they are also excellent communicators.