Well, first you need to find the "
line of action" for each figure you draw. Otherwise you're drawing will look stiff, like yours does.
Second, your figure looks very uncomfortable and unnatural, like he doesn't know what to do with that free hand - likely because YOU didn't know what to do with that free hand. No one stands with their hands limply at their sides. Every pose your character assumes should tell you something about their personality. Look at each of the two photos.
Photo One. Photo Two. Every person is standing in a static or casual pose, but each of their choices on how to stand tells you a lot about their personality and how they are feeling.
Third, your line work is very weak. All your lines have the same width and emphasis, with no variation. Lines need to be thicker where there is shadow, or where the object is closer to the viewer. Lines should be thinner on brightly lit areas or where the object is farther from the viewer. Long lines should be thicker in the middle and taper towards the ends as a general rule. There are more considerations than this, but if you don't having varying
line weights your image comes up looking lifeless.
Fourth, the clothes on your figure look very ill-fitting. This makes it look as if you have a poor grasp of the underlying anatomy. A lot of that ill-fitting look in this image is caused by your excess of detail on your wrinkles. You've added a lot of wrinkles and folds without properly following where wrinkles and folds would actually form and behave on this figure in this pose. Study real fabrics and clothing, use reference, and understand why wrinkles or folds happen - either because the clothing is being pulled, pinched, draping, or folding.
The accessories like the gun holder and gun aren't drawn correctly on the figure either, so they feel like they are floating on top. Again part of this is simply research and reference. For one, holsters are worn under suit jackets, never over, the straps must be closer in to the neck to provide support (you have the straps resting on what would just be padding in a real suit) and the gun is hanging much too high. The point of a holster is easy and quick access. This seems like nitpicking I know, but professional artists look this stuff up and use reference. With Google Image search we artists have no excuse not to use reference these days. And that is another big tip - use reference. Don't slavishly copy, but ALL professional artists use reference. We have filing cabinets full of the stuff, and often take pictures ourselves. This
article on IO9 gives a good overview of how a professional artist tackles a piece and how they use reference.
Fifth, the hair. Again, this is a case of studying actual hair and how it clumps and behaves, and not trying to fit in every line or hair. The hair in this case is also clinging quite stubbornly to the shape of the head, causing tangential lines (where two lines flow directly into each other like they are the same line) where the hair meets the cheeks. Your coloring also doesn't make sense for how you have drawn the bangs on the forehead - we should be seeing skin the way it is now. In general, drawing and coloring it should take as long as the figure did by itself - if you are doing it well.
Finally, coloring. Auro-Cyanide was right to congratulate you on using purple in shading the white shirt - much better than gray! But you used gray to shade the suit. Gray or black should almost never be used for shading. In fact, you should probably avoid black as much as possible anyway. You need to study colors and color mixing, and really learn to see various colors. Look at the image below:
It is a stone wall, and most people think of stone as being gray, but notice how poor and anemic the stone wall on the right looks when painting with nothing but grays. Now look at the stone wall on the left painted in blues and greens. It still READS as gray to an observer (especially if the actual gray wall isn't beside it - go on cover up the right side with your hand) but it looks MUCH more rich.
Another example, this time by the great Jo Chen.
We all know that the Punisher's outfit is black, right? But Chen didn't use any black to paint this picture. Punisher's coat and shirt and gloves are painted with browns, greens, yellows, and dark reds. Notice also how the coat reads as leather due to the way it folds and the highlights on it. Notice too that none of those highlights on the jacket or even the skull on his shirt are painted with a pure white, only creamy light yellows.
Your skin needs other colors than shades of peach and white as well. Skin is made up of a lot of different colors - blues, reds, yellows, golds. Skin is paler and has more blue the thinner it is or the closer blood vessels are to the surface, and areas like the nose, ears, and fingertips that are exposed to the most sun or changes in temperature are usually more red. The take away here is to avoid white in skin, and use multiple colors.
And yes, use contrast in your coloring. Colors without strong contrast look weak and flat.
I won't touch the anatomy as you've asked me not to and I know you're aware of it.
I hope all this helped, and if you need any clarification I'll be glad to try and answer any further questions.
I know the first time I realised how much olive green was in some skin tones I was surprised out how much difference it made.
)
hahaha how embarrassing! And wow! So shiny! 
