SHADING EDIT GO GO GO
Err, I'll try to keep it quick!
Without criticizing the lines and colours I want to raise some points regarding the shading.
What you're doing now is more or less subtle pillow shading, that is to say, you fill an area with a colour and then you buffer it with a shade colour where it touches the outline! O:
Thing is, it makes stuff look like .. err .. pillows? Well, with the subtle colour scheme you're using it doesn't look like huge blobs, which is a good thing! Anyhow.
Picture 1: It's your picture! The left leg, I feel, looks extremely flat with some bumps. Do you see what I mean? It feels like it's made out of pillows, but still without a lot of depth.
It also appears to me that the light source is directly in front of him. That's a bit weird, either he's standing in front of a lamp or it's dusk/dawn. Just something to think about!
Then the right leg (i mean our right), here I just emphasized how the equal priority makes everything feel like it's made out of the same kind of blobs. The image next to it is there to emphasize how everything seems to be the same kind of blob shape! It doesn't really LOOK like that, but it's an explanation of WHY my brain gets the 'somthing is off' feel here. Since we probably don't want that, let's do something about it!
Picture 2: This is simple: It's your picture with all shading removed. It's MUUUCH easier to reshade stuff if you actually just wipe all colours and go from there. PLEASE try it! Be brave! Destroy your stuff! This is digital art, you can always save something and go back to it later! Destruction is essential for creation!
Also note how I added some of the black he's got in his eyes there in the outlines. Also trying to defeat flatness! More contrast helps tricking the eye into seeing depth in a 2d image!
Note the arrow. It points towards a middle-stage between 2 and 3. I just blotched out where the highlights WOULD be on the leg if the lightsource came from above. With practise this comes easier and easier and It shouldn't need to take lots of time.
HERE IT IS ESSENTIAL THAT YOU DON'T GO INTO DETAILING MODE! You know when you just stop thinking about what you're doing and just go ahead and fill in the little spots and play around with details - do away with that in this stage! You have to think about visual priority and WHERE the light hits the surfaces STRAIGHT ON, and place the highlights there. Think like a computer!
And yeah. Picture 3: I just threw in highlights here and there, note how I make some areas decidedly bright and others decidedly dark, see, you don't need to use all shades everywhere - it looks smoother if you DON'T and take care to place the colours where they MATTER! I also raised the light source. Take note of the side-leg reference, and how I tried placing my shades to where the light hits stuff - combined with emphasizing parts that are important for the viewer, such as where the knee is, etc, to make it easier for the viewer to understand what he's looking at!
Also note that the foot, running with this logic, should probably be brighter in my edit. Right on the top.
ALSO:
A/B:
This is an example of banding! I urge you to zoom in and study the staircase banding going on here! See that when each band of shading switch lanes at the same time - it all looks completely disjointed!
A has banding, it's taken from the side of the body of picture 1, but with extreme colours.
B is an example of how using carefully placed buffer shades you can create more smooth results with the same colours. Although it's flawed, I used just a single pixel at one stage and that just makes the curve stick out in a bad way. Heh. Don't do that!
This image might also help!