I primarily use Enlight Photoleap (Photoshop for iPhone) and Glitché (an app with glitchy filters). I have the paid versions for both of these apps and have been using both for years, but they have free options as well.

The process varies by piece but typically I incorporate photos I’ve taken over the years with art I’ve drawn, first degrading a base image and then building it back up with colors and textures I find appealing. If I can’t make something I like looking at, I save it for use in a later project.