Welcome to Gaia! ::

Hmm... the pose and facial expression looks nice
But I think his hands looks a bit odd
You should practicing more on the hands.

For example:
His left hand --> the base of every except thumb should start at the same position, here in the picture it seems like the ring finger and the small finger is longer because it start earlier from the palm. (look at the line between these two finger you'll see that it's too long)
And the tip of every finger.. Must NOT be in the same position, or it'll looks like square

Anyway, this is still a good picture
I give you 8 out of 10 3nodding

The most obvious thing is the hands. They are different sizes to start. The hand that is on his knee has a very short thumb. The other one has almost no palm at all.

Then the colouring. I'm actually curious as to how you go about it. You seem to use black in your shading, that is not a good idea. It makes the colours very muddy and dull. It is better to use a darker version of orange here. Same with the highlights, you should never use pure white to highlight. Use a brighter shade of the original colour, unless you have an oddly coloured light source. (Such as, a blue coloured lamp casting blue highlights, etc.)

Also, everything in the picture has the same texture to it. The metal is coloured in the same was as the fur and skin and cloth. This is because you seem to be using the same kind of brush for everything. Use different kinds of brushes on different kinds of objects. You seem to be using only airbrush or something similar. It gives a very soft look to try only to use it on soft things that don't have very defined edges. Use harder brushes for things like metal.

Also, did you ink it and then scan it, or ink it digitally? The lines are all very thick and dark. There is something called line weight that you should consider. Some lines should be thin, while others are thick. For example, using thinner lines in places that are clsoe to light, and thicker ones and you move into shadow. Changing the thickness of lines helps things to look more dynamic and interesting.

The picture itself is very nice, but I do think that the murkyness from all the black shadows takes away from it. Don't be discouraged, though! It takes a lot of practice to learn to colour well.

It could be my mistake, the highlights on the clothing look like you used white with a low opacity to make them.

I would like to see your 'normal' picture. I still think that the muddy look doesn't quite work here. If you're trying to make it look like a very shady forest, the background is much to sunny looking and darker versions of the colours you used would still be better than using so much pure black.

You should experiment with all of the tools in photoshop, to see how they look. PS 6.0 should still come with more than one brush. Also try playing with the opacity/pressure of the brush as well. Even if you can't find a tutorial, just plain 'ol messing around with them should help.