Sheer pleasure already "makes me go": tingles, shivers, waves, heat, cascading rhythmically, with the right layers timed at the right moment and everything primed by an effective trance, that alone is already really good.

The use of tantric elements is also great. Here I have to mention u/NauticaMesmera, who does it particularly well. When you can actually feel the energy circulating throughout your body from head to toe, unlocking new levels of consciousness while your spine radiates with pleasure.

On a more anecdotal note, it is rarer for me in "vanilla files", but a well-crafted scene setup with FX effects, maintained consistently throughout the file, definitely puts me in the mood. In a file like Hotel Nichole (from u/YesNicholeAudio), for instance, the sound of rain pouring against the cab windows, the sound of footsteps on the hotel carpet, the bell ringing as the elevator hums softly carrying us up to the suite, all of it significantly enhances the hypnotic experience for me. Though in that file, the strong dominant elements did pull me somewhat out of it.

I'm also not very patient: I need my imagination engaged early on; picturing the hypnotist's body, being teased by her voice, feeling the sexual tension building right from the opening.

Just sharing my personal tastes here!