First, decide what your style objective is.

Start by asking yourself two questions:

1. Who are you presenting to?

For example: Are you speaking to a group of high school students, or an audience of high-powered executives?

2. What are you going to be speaking about?

For instance, are you giving a formal sales presentation or an informal talk?

This will help you decide if you want to convey authority and seriousness with your outfit or if a more laid-back look would be appropriate.