I learned that paragraphs should be indented with a tab set at five spaces. I'd say that conventions are not universal, so please yourself, to the extent that tools and bosses allow. I follow conventions that make sense to me, or that I haven't thought about, skip those that don't.

I usually indicate paragraphs these days with double returns (not carriage returns) with no indent, but there are times I indent, and sometimes even use both methods. Amount of indent, if any, I determine by eye. Most of the publications I set up or write for are programs for performing arts, and I have nearly free rein.

Peter