Excel basics for co-workers - brainstorm

Hi all, I'm putting together small excel trainings for my co-workers. They are accountants and administrative staff. I feel disconnected from what is elementary (or what people with excel phobia are fearing) and may be useful to them to increase efficiency / reduce stress in their daily work lives. I've asked if there's anything they want learn and have been researching what's included in the excel classes.

-Is there anything you wish your co-workers understood better about using excel and you wish you could teach them to improve on?

-Is there anything you wish someone had showed you before you stumbled upon it accidently?

-Is there anything that as a new excel user you feel afraid of?

I had a coworker say she didn't trust the lookup_value would work and find the right data, even set to exact match. Another is afraid to use formulas.

I apologize if I haven't labeled this appropriately or this isn't an appropriate post. In working on this I wasn't expecting the fear people have working with excel and am interested in your experience. Eidt: format