For each scene, establish a point of view character and stick to it. If you find yourself throwing in other characters thoughts or feelings, see if you can get rid of them without hurting the scene. This narrows the POV to one character.

Once you’re that far, check the scene for anything the character can’t know, but you’ve described. There’s a good chance this is telling. It might be something that can be removed or put in as part of what the character is doing. This way you’re revealing the character’s experience and not what you as an author want the reader to know.

I’m not saying write your whole novel this way. I’m not even saying this works. What it does is give me a process to check if I’m telling and not showing. Then I can decide whether or not to make changes.

If you have other ways to check if for telling versus showing, I’d love to hear them.