My advice is always the same, but a study from Abraham Rutchick, a professor of psychology at California State University, adds a new wrinkle.
Here are my three suggestions, followed by the study’s finding:
1. Dress a little better than the audience.
As the speaker, you are the authority. Your clothes should convey that authority. If the audience is in business casual and you show up in shorts and a Hawaiian shirt, you’re going to look like you crashed the party, not like the speaker. Do your research, find out what everyone in the audience will be wearing, and go one better.
Our first impression of you, the speaker, is visual, and so it’s doubly important that the first impression fulfill the audience’s expectations of a good thing coming, and the idea that there’s an expert in the house. Don’t dress like the guys in “Dumb and Dumberer.” You’re there to delight and instruct the audience, not to pander or disappoint them.