The method I've been using at the moment has been to do everything in grayscale and then paint color in on an overlay layer. This inevitably screwed up my colors until I saw a tutorial by Sycra in which he recommends that you reference this color value chart when laying down colors:
Since I'm not totally savvy with photoshop yet (I use CS6), I'm asking if there is another way of going about this. Do you paint from grayscale to color? Why or why not? Is there another method than the one I've mentioned or I just need to practice until I get a subconscious sense of color-value relationships?