How to Make Beautiful Excel Spreadsheets

Hello! I want to design a "beautiful" excel doc. I am making a tool for creatives to use and we're a very aesthetically-sensitive bunch.

I found this guy called Josh who runs Excel + Design, but I think he's too busy, so I'd love to try my hand at it.

I know this probably isn't a usual request, but if you know of resources that would help me figure out how to do this, I would be very grateful! Thank you!