i have long dreamed of making a cli/tui design course at some point, but the thought that any principles would immediately get slurped up and repackaged as "skills" is so demotivating
go study print design (hierarchy, layout) and figure out what levers exist within the constraints of a terminal
use shape, color, and (most important) space
read the unicode spec to find lil glyphs, assign them meaning
read the elements of typographic style
play old video games, note the constraints that make them fun
pretend you're designing a mobile app
try to make something you've never seen before