I suggest getting some plastic spoons and spraying one whenever you get a new color or try a new technique. They're cheap and plentiful, so you won't get any surprises when you paint your model. I also keep my spoons with new colors and use them as a color guide whenever I decide on a color scheme for new builds.
My go-to "black" is Mr. Color Cowling Color. It reads as black, but is lighter than a pure black, so details aren't hidden as much. Gaianotes Neutral Grey V is another option for this.