Improve Color Harmony by Studying Hiroshi Yoshida
Hiroshi Yoshida was a 20th-century Japanese artist who's skill as a woodblock printer was unmatched.
I base most of what I know of color off this artist's work.
Notice in this group of prints that each one has a distinctive color set. Each image has its own dominant hue, in total harmony, with excellent design and atmosphere.
Also notice that there isn't a soft edge to be found.
All the "edgeless" brushwork in the world won't turn a poorly designed, color discordant mess into a work of art...ain't gonna happen.
Learn the tools to forget the tools!