Ask HN: What would attract you to attend a 1day course on a tech of your choice?

I'm going to be delivering a 1 day irl intro course to d3.js. I'm trying to put together a format and offering that will stand out.

Regardless of the tech, what would (or wouldn't) attract you to attend?

E.g. Credentials of the instructor? Supported time to work on a self-directed project? 1 on 1 time? Etc.