Few things do better to set the table than an appropriate soundtrack, especially in remote play. Keep a massive library of curated playlists in Spotify, categorized by atmosphere, locale, creature type, and combat. Playlists are useful if they're organized in such a way that all you have to do is click shuffle and play, and rest assured knowing that any music in the list will suit the situation at hand.
To this end, here are some ways to consider organizing your playlists.
By Set Piece
Think about the way your adventure breaks down into scenes: will there be downtime conversations around campfires? An epic battle? Are they investigating a mystery? Swashbuckling on the high seas? In this way, you map playlists to the mood of the scene.
Break your playlists down by individual emotions, this way all you have to think about is how you want your players to feel when reaching for a playlist. With this approach, it's best to make as many playlists as possible, so you can capture everything from "Disturbing" to "Ridiculous" if the opportunity arises.
Consider the physical places your players will go: a big capital city, the frozen north, a carnival, cathedral, the wilds, a tavern, and so forth. Such auditory transitions help players navigate the imagined space and enhance the theater of mind experience.
This works especially well for one-shots, where there aren't a whole lot of scenes to explore and things tend to be on rails. If you're running a one-shot set in the Wild West, then you can draw from the scores of iconic cowboy movies. If you're sending your players into some kind of deadly tomb, why not put on a mix of Indiana Jones, Tomb Raider, and The Mummy?
Sometimes a sense of place is accomplished by mirroring the imagined space with that of a known reality. If the players are traveling into a forbidden jungle continent or a mystical monastery, you can pair those fictional locations with music from matching real world cultures.
Always keep a separate list of combat encounter soundtracks, categorized by the quality of the fight. Is this the final battle with the BBEG, or a skirmish with a bunch of goblins? Is the battle taking place in the necromancer's creepy lair? An appropriate soundtrack during a combat encounter can inspire players to take heroic action (or flee!).
While streaming music services like Spotify and YouTube are your friend for live music during the game, our two favorite resources for royalty-free music in post production are FilmMusic.io and Tabletop Audio.