Mark,
Well it's an exceptional first piece! I have Franks book somewhere here in the Studio if it hasn't walked elsewhere (which I think it has). It's a very helpful one. Shape, shadow, tone, color. Under the heading of color would be intensity ,as well as hue, warm and cold. Non-intense tends more toward gray or neutrality.
If I remember correctly, Covino was into what he called "controlled painting" where color intensity was altered with the addition of a gray on the same value scale as the color. An interesting and useful method with it's own look. So if you want to mute a blue that is a value of #3 on the scale, you add a value #3 gray to it untill it's intensity lessens the desired amount. This is different than mixing a complimentary color in to neutralize it.
That's something worth playing with in your next piece. grayer as space recedes, and grayer in the shadow areas (now I don't mean gray color, I mean less intense color from the addition of gray). Some warm and cool color also, most especially in the larger color areas.
Covino's Grissaille has similarities to the dead layer.
I haven't gotten one yet (I've only just discovered this site), but getting one of ALexie's videos would likely be a big help. While it can certainly be done, learning from a book is a tough road. I say that even though I have a whole wall of them. You can pick up things that aren't thought to be written from watching. I have stumbled about on my own for the most part, often taking a good deal of time re-inventing the wheel.
As for color, time, painting, mixing, and doing up some color charts experimenting with tints, compliment mixes, and gray additions, will eventually get you there.
Heck man start another painting,
Carl