Quick four-minute video on using black and white adjustment layers to edit color images in Photoshop.
When they are thinking black and white, most people use the black and white adjustment layer in Photoshop. However, suppose you change the blend mode of that adjustment layer. In that case, you can use the adjustment layer for controlling the luminosity and color in the image. The nice part about this process is that it works similarly to a luminosity mask, making the adjustment automatically and proportionally to its strength. I also like to use this technique to isolate color and use the isolation for making a mask to use on other adjustment layers.