Practicing art, and how that relates to music

I grew up studying music: three different instruments in fact. That's a lot of practicing each day! So I have a lot of music study experience with a framework for practice. I loved to draw as a child but art was just another subject at school, not a major part of my extra-curricular life. I have never studied or practiced art in an even vaguely organized manner.

Does this matter? I believe it does.

In The Art of Learning Josh Waitzkin suggests that to be good at a skill, really good, you must learn the basics in depth. Twyla Tharp agrees with this opinion in The Creative Habit, giving the example of the exercises a ballerina does each and every day. Not that I think there isn't a place for free-wheeling work, or for exercises that help one to become more creative. I truly think that it's easier to free your creativity when you are also working on improving those basic skills.

But what are those basic skills? I thought about all the music exercises I did as a child and tried to think of the visual art equivalent and I came up with the following:

Music	Art
Scales & Arpeggios	Drawing & Mark-making
Studies	Studies of Values, Color, Composition
Improvising	Preliminary work for paintings, Sketchbook use
Music theory	Art history
Instrument care	Knowledge of materials - paint, mediums, papers, canvas etc.

Having grown up with a framework for music practice I'm interested to find an equivalent structure for improving my visual art skills. I'm always interested in learning: if you see any skills I have missed in the list please let me know!