...at my school, we're basically given a few pointers on the programs and told to learn the rest on our own.
You don't want to get me started on the subject of what passes for "teaching" computer graphics these days. The first thing that should have been taught is the fundamental difference between the two "hemispheres" of the digital graphics world: Raster- versus vector-based graphics.
I'm used to Photoshop "painting" on my own.
There's a reason why raster-imaging programs and vector-based illustration programs have since the beginning been casually called "paint" programs and "draw" programs, respectively.
When you "paint" in a raster imaging program, you are essentially dealing with a single object: a single raster image. When you use the "painting tools" in such a program, you are simply assigning different colors to the pixels in that single image. You make a swipe with a "brush"; the program tracks the pixels your cursor is in proximity to and assigns them different color values. That's done. The raster image still has the same number of pixels (color values) when you then do the same thing for your next swipe. The file doesn't grow as you make more swipes, because it's still just one rectangular array of color values.
When you "draw" in a vector-based illustration program, each swipe with a freeform "brush" or "pencil" tool (the so-called "painterly" tools) creates a new mathematically-described shape. Each swipe adds to the list (the object stack) of the objects in the document.
I've often thought we'd all be better off had vector drawing programs never tried to feign being what they're not by adding the so-called "painterly" swiping tools.
Don't think of a "brush" feature in a vector drawing program like a "brush" in a raster imaging program. A vector-based "brush" is more like an envelope; a mathematically-described routine for distorting a path or a collection of paths stored as the "brush." Raster and vector "brushes" are entirely different things.
The most common stumbling block for beginners in vector drawing programs is Photoshop (or something similar). Forget Photoshop when working in a program like Illustrator. They represent two entirely different sides of the graphics world. That's why they both exist.
JET