There are six elements in my world: fire, water, earth, air, lightning, and ice. For each element, there are beings made entirely of that element. I have two issues: One, I'm not sure how to make a humanoid being out of some of the elements, and Two, I need a 'dark' version of each elemental. Help with either would be appreciated.

Ice:
About the size of a human, made completely of ice, with a wispy cloud of frost vapor around it. Color can vary from completely transparent to a bluish-white. Lots of spiky icicle bits, especially on the back and on top of the head, like hair.
Issues: I'm not sure how the face should look, or how the evil version should look.
Fire:
Also about the size of a human, but much less distinctly shaped. Essentially just a swirling pillar of fire that can sprout whatever limbs it needs. Can grow larger, but not much bigger than twice its size without consuming something flammable.
Evil:
The flames are purplish, and it has more of a cyclone-like aspect, and when it creates limbs, they have a more spiky, solid look to them.
Issues: Again, the face. Otherwise, fire is pretty simple.

Air Issues:
Air pretty much is one big issue. >_< Most stories/games/movies that have air elementals represent them as being made of clouds, but I don't like that. For one thing, clouds are mostly water, not air (yes, they are airy water, but still), and for another, I want the air elementals in my story to have a more ethereal quality. Less like a floaty puffy cloud and more like the wind. So I need help with the normal elementals, as well as their evil version.
Earth:
About twice the size of a human, earth elementals are made up of large boulders and smaller rocks bound together with dirt and sand. The fists, feet, head, and torso are each a single stone, unless it needs to grab something, in which case it can split up the stone on its hands or feet. The face is just made up of cracks in the stone it's using as its face.
Evil:
As opposed to the natural earthy colors of the normal part, the evil earth elemental looks like it is made entirely out of obsidian, glistening and black. The face is now made by glowing gems inside the cracks in the head, giving off purple and red light.
Issues:
None, really, unless you want to comment.
Water Issues:
Another problematic one. I've seen water elementals that look like fish people and I've seen water elementals that look like human-shaped sacks full of water, and they both struck me as equally unlikely. Any input would be appreciated.
Lightning:
Seen just as often as nothing more than a floating ball as they are seen in their humanoid form, lightning elementals are the most changing and impulsive. Their humanoid forms grow and shrink constantly, sprouting new limbs and losing old ones. Their face, when they choose to have a face, is made up merely of darker energy than makes up their body.
Evil:
Evil lightning elementals lose much of their childish impulsiveness, becoming much steadier. They are often pure black, occasionally purple or red, with a color different than their body for their face.
Issues:
I'm just not sure if that *points up at it* is good or not.