You have managed a convex highlight on the planets, but somehow you have done something strange on the gray alien head (I assume the head is supposed to be somewhat round, not flat like a pancake).

Either the highlight should be convex, meaning the light source is in front of the head, like this:
http://art-smart.townofmanchester.org/how_to/images/bubbles_shading.jpg

Or else, if the head is back-lit, the shadow should be convex, like this:
http://upload.wikimedia.org/wikipedia/commons/thumb/7/79/Sphere_with_soft_shadow.jpg/250px-Sphere_with_soft_shadow.jpg

If both highlight and shadow are hollow, it means it is a pancake, doesn't it?

If the beard was affected by the wind, I guess the tip of the beard would be affected most.
I see you have reduced the opposite bend in the hat, which in my opinion doesn't make the wind theory more correct at all.

I think I liked the first brown bundle best, without the stick. When you colored it red, my first thought would have been that it is a bloody heart.
In my eyes, the main problem is the stick.
I might suggest making the stick thinner and curved with the weight, making it look weaker, more like a straw than like a comparable weapon to the dagger (don't mind the rest, I got carried away, it looks more like "wolves, beware"):

Also, Do you really want the right hand elbow to be this sharp, or is it a sketching accident?
And to me the hands color does not look like a problem.

Another question is, the pose is extremely idle, why? Does the gnome have nothing to do? Maybe the head could be looking in a different direction than the body, like looking if there are wolves around, making it more dynamic, like this: http://en.wikipedia.org/wiki/File:Rembrandt_Harmensz._van_Rijn_035.jpg

For purists, the beard shape would probably also make more sense now, following the head looking left and right.

Edit: looked at some earlier post, where you mentioned animating it and maybe the previous suggestion was all wrong, so also did this pose for fun (based on a photograph of statue of Bruce Lee):

Reduced size because I feel more comfortable at smaller sizes.
I wonder if the full shadow is dark enough now.

The shading should be OK now as far as I can tell, but somehow it doesn't feel quite right.
Light direction is like the yellow arrow in previous post.
Cast shadow is straight down, though (inconsistent, I know, but they do that in some places).

I am trying to learn how to draw with flat shadows, and concentrate more on the highlights. If you are wondering why, it is because there will be less details cluttering the image. I would like to understand what would be the minimum to define the form.
One of my inspirations is http://commons.wikimedia.org/wiki/File:Cat_walking_DSC08739.jpg.
Therefore I feel reluctant to use some light to define the full shadow parts explicitly, and I hope the brain will fill it in on its own, based on the expectations created by the highlights. That was a bit too big words for such simple purpose, but my English is not good enough to make it sound exactly how I intended.

That said, I would appreciate either advice that could help me become better in this direction, or else I hope you point out how I am mistaken and on an impossible or inferior quest. If someone knows where I could find examples of such thing having been done by other people, would also be helpful (because the only examples I have found myself so far are backgrounds in foggy distance, but they don't have much highlights either).

Gave it a cheekbone, changed the curve on the body highlight to more radical, and adjusted left hand palm a bit:


The highlight on the arm seemed overdone, reduced it and I like the result a bit more now.
Also, put it on dark background to remove some unnecessary details, I hope it still looks like a dragon to other people.
I am still not completely convinced by the palette or the shading, or maybe the anatomy looks unnatural.

bubbles start from the bottom plane of the glass and follow a mostly straight, continuous line upwards (again, in carbonated drinks at least)

That would mean... the glass is not extremely clean. Bubbles preferably start from points of disturbance in the fabric of space-time continuum, say, a piece of dust. That said, when you see straight lines of bubbles, the glass might still be reasonably clean. To my knowledge, chaotic bubbles (no lines) is a sign of extremely clean glass.

And then I had some surprises looking at some references.
Googled "fizzy bubbles" and found that more often than not the bubbles appear surprisingly lighter than I expected, maybe dependent on background. What I expected was that bubbles would have average same darks and lights as the rest of the glass bottle (except being round). There is, by the way an angle of reflection (I hope that is what it is called), so in the center I would expect the bubble to be more transparent, and at the sides it should reflect whatever there is to reflect. Surprisingly, I couldn't find a good illustration for that, this one was the best (the further the water, i.e. smaller angle, the more reflection and the less bottom you see): http://www.visualphotos.com/image/2x6561704/two_dogs_looking_down_at_their_reflections_in_the

From AlcopopStar's latest post, with removal of the part of the cheek that should in my opinion be not visible because it should be curved away from the viewer.