Was trying to find a way to go from a muted coloring to a more vibrant one without it seeming weird and stumbled apon the whole greyscale thing on my Youtube feed.
Its not exactly what I was looking for but I think it can do it, so wanna explore this more.. maybe with a happier subject :P (I just started to draw and sad lily just happened.. well, she seems more pissed off ngl)

Since I havent done greyscale too well before I just followed along without much experimenting, just learning. What I'm noticeing is my shadeing and highlights were a bit off in the past, the greys make it a lot clearer where things are supposed to be and where you might of missed. Only downside is that it leans to a more blended style.
I then used clipping masks and layer effects to get the color ontop of the greys without changeing the gradients and tones... Values? They said values a lot in the video, think that just means how bright and dark it is.

Anyway, got a few ideas I wanna try now, and shareing that stuff wont spoil anything.