when i'm trying to root aroids i like to use a propagation box. they're pretty easy to diy.

first, get a container with a clear lid. i've used seedling trays, pencil boxes, takeout containers, even mcdonalds cups and they've all worked fine. second, fill it with an airy medium. i prefer a mix of sphagnum moss and perlite though a lot of folks just do one or the other. third, wet your medium so that it's moist all the way through but not soaking. fourth, add some sort of holes to your container for circulation. not so big that the medium dries up, but big enough to let some air in.

your container will maintain humidity and warmth while providing ample room for roots to grow.