A good while back, I contributed an article called Clean Up Your Narration to Write to Done. It includes advice on ‘showing, not telling’ via dialog, sticking to once tense, and putting the important stuff first.
Here’s the first two paragraphs:
I have yet to read an all-dialog novel. In fiction, narration is critical for establishing many elements, including scenery, character appearance, and action.
Despite (or perhaps because of) its importance, smooth narration is one of the hardest skills for an aspiring writer to master. It’s easy to get lost in long, flowery paragraphs of clever prose stuffed with adjectives, adverbs, undecipherable in-jokes, and repetition.
Here’s the basic outline: