As a digital illustrator and 3D modeler I'm a little biased towards digital.
There are several programs out there for free that are awesome.
Krita is a painting program that can simulate watercolor,oils, pencil, chalk, markers, ink, all kinds of stuff.
Inkscape is a vector program that great for more graphic style art.
Gimp has painting ability also, though it's more of a photomanipulation program.
Blender is a 3D modeling and animation program that's practically industry standard.
All of these are
FREE.
I use them all.
I got a Huion 680S pen tablet to draw with for around $60
https://d-alien.com
They leave no mess.
You can make mistakes and take risks without creating waste because you can always hit Ctrl>Z
You use almost no resources (except electricity)
Once you have your art exactly like you want it, you can now print it on anything, any size - canvas, mugs, T-shirts, greeting cards.
No mess
no waste