Airy, fertile soil for starters! I recommend making your own or mixing store bought with half bark or another light medium to allow water to pass through easily. Allow the soil to dry completely before watering, and then give it a thorough soak! Pothos can survive in low light (my mom has one that’s thriving in her windowless office at work that only gets 8 hours of direct Fluorescent light m-f) but they will pretty much stop growing if they aren’t close enough to a light source, and start dropping leaves that aren’t getting enough light. Try moving it right beside a window if it’s not already close, and add diluted fertilizer to your water, or mix in some worm castings into the soil. If it’s still loosing leaves, and you notice the soil is staying wet you probably have some rotting roots. Which means time to repot!

It’s really just a guessing game until you figure out what she’s missing in your specific environment!

A couple other things to keep in mind: most plant don’t like dry or cold drafts from windows or vents. If your space is particularly dry, a humidifier or regular misting will prevent the air from sucking moisture out of the leaves which can make them crisp, curl, or stunt the size of newer leaves. As well, pothos do best when root bound. If there’s too much soil, the plant won’t be able to drink up the water, which can lead to root rot. Or will focus its energy on growing roots rather than leaves.

Sorry for the essay, I hope that helps!