With a good color wheel, you can see what will come out when you mix two colors. Pick the two colors in the color wheel, and the color in between will be the outcome. It only works well when the colors are not too far apart in the color wheel. Opposites in the color wheel will make smudgy, greyish-brownish colors.
Artists do not use the color wheel. STUDENTS use the color wheel to learn about color harmony. The direct compliment of blue is orange, so blue is directly opposite of orange on the color wheel. Mixing two compliments (blue and orange) will give you a neutral color, gray (brownish, if using cheap paint). This is only one simple example of a color wheel's use. Again, a color wheel is for the learning of color harmony.