Newbie here - Adding Icons to Rise Courses - Best Practices?

You can use UNICODE symbols or Emoji pretty much anywhere in text. 

Hi Ti, welcome aboard. It sounds like you're trying to insert a custom image/icon inside a paragraph, heading, or table, many users request this and there is no built-in feature that I'm aware of. I built my own workaround that uses the new Equation Editor in Rise and icons from icons8.com. It's a bit experimental, and shows some of the improvements you can do with CSS. 

If you have Storyline or Studio installed.  You can easily access the icon library in those tools, then save them as a picture.