I looking for any suggestions for one taking their first trip. Will be alone from Detroit to Chicago (I know, not far but it is what it is) for a convention.

I've heard I should book business vs coach. Anything else I should know? The whole luggage thing confuses me. I've heard they don't check luggage, then I hear they do. If they don't, I just carry it on?
Thanks for any ideas and tips.
Rhonda