Inserting description

Hopefully, Robert, you're reading dozens of books in your genre and seeing how other authors accomplish, or don't accomplish, this.

I'm a minimalist, so I don't generally describe characters. It's enough to imply their age and perhaps their height, if it's important. Say a man is tall and good-looking. That doesn't need to be described. It should naturally come out in dialogue.

Let readers see your characters however they want. Just don't surprise them by having someone suddenly appear portly or limping or ugly. Also don't surprise the reader with someone's ethnicity. That should probably be clear from their name or maybe their accent, but as I say, don't have them onstage for several pages before it becomes obvious.