Read novels. Nobody talks about this much but it’s a great way to understand the world you’re playing in. I’ve recently finished The Cleric Quintet by R.A. Salvatore and, whilst I wouldn’t recommend his books from a literary point of view, they give a good insight into the Forgotten Realms. I’ve now moved on to the Dark Elf Trilogy. It’s a better series of books but based in the Underdark so not as useful from a lore perspective…yet.
If your campaign isn’t set in the Forgotten Realms just read general fantasy novels. A lot. Focus on the syntax, the adjectives and the verbs, and really appreciate the language used. Begin incorporating this into your descriptions.
I recommend absolutely anything by Brandon Sanderson!
“…avoid using the word ‘very’ because it’s lazy. A man is not very tired, he is exhausted. Don’t use very sad, use morose. Language was invented for one reason, boys – to woo women – and, in that endeavour, laziness will not do.”
N.H. Kleinbaum, Dead Poets Society
If you haven’t the movie, please go away and do so immediately. In case nobody told you, Dungeons and Dragons is literature in spoken form. Consider this homework!
Matt Colville, whose Running the Game videos have taught me so much created a video called Verbs. In that video, he discussed the usage of language to improve your narration and it’s definitely worth watching. I think he missed a trick here because he should also have considered adjectives but it’s a good place to start.
I highly recommend that you do some searching for “Verb lists for DnD” or “Adjectives for DnD”
Instead of hit, learn how to use words like “Strike”, “Impact”, “Smash”, “Bludgeon”. Instead of “Sneak” use “Infiltrate”, “Steal”, “Slip”, “Tip-Toe” or “Slink”.
This is gold! Print it out and stick it to your monitor or DM screen.