Here I'm posting some of my study and process about values. I'm trying to improve and create some kind of reality with just a few strokes, based on some theory from the masters of traditional painting. The only way to improve my shitty art is studying as hell, every goddamn day.
As you can see I start with just a very loose line for proportions and pose, then I jump into the 4 values step (some people use just a range of 3 values or more than 6, just try to find the one that really fits you) this makes me focus on light and shadows as the main priority without thinking in colour yet.
Then I drop a Color Layer, adding some tones (not too saturated, come on) this brings a little bit of life to the painting.
The Overlay Layer will just get this saturation we were looking to get in the Color Layer (EFFING GREAT), so, try to use the same tones you used already, always playing with variations of warm or cold tones. Depending on the light you can use in the Overlay Layer, warm tones like reds, oranges and purples and blues for the shadows, this will create a nice transition between tones, oh yeah.
We already have values and tones on the board, but we need more shadows, this is where the Multiply Layer comes in handy. Using just black and a soft brush, try to intensify those zones you need to create some gradation between values.
The final step are lights. I use to create another Overlay Layer and pick a light-red colour (almost white) and apply some highlights with a soft brush in those spots I want the eye focus on. Some of you would say "why you don't use yellow for highlights?" Because red is passion and I LOVE painting!
Next, I add some pure white dots for a wet look, remember wet surfaces just shine in little proportions just to exposure the texture of the material (nerdgasm incoming).
For more detailed illustrations the process is more or less the same, just need to spend more time to push it up, exploring and understanding the conception of what's going to be born.
Hope you like this mini tutorial, I would like to hear from you and if you tried all the lies and bullshit I just wrote before!