Here is what I have noticed with your pictures, and no, this is not a bad thing. (I'll do my best to explain this understandably...I'm horrible at expressing what I mean into words)
I think that you judge the artisticness of things more by the content. You tend to take shots that have a bit of shock value, and/or make you think. This is a good thing. It is my opinion that your posts do stand out from others. Your pictures are remembered. But...Also in my opinion, people on this forum tend to critique while thinking about the rules and guidelines of photography; lighting, composition, etc, and maybe not so much about the actual content or subject. Does that make sense? Now...I think if you stuck with this same idea, but did a reshoot, you can make it work. Try and use natural light..the onboard flash tends to wash out skintones, and you usually want to try and get skin tones as close to natural as possible. One thing I do to help that, is I take a tissue and I have it rigged up, covering the flash, so light still gets through, but it diffuses it. Another thing to think about is composition. You don't want a busy background, that takes away from your subject. Look out for posts and tree limbs and things like that which might look like they are 'growing out of your head'. Also, follow the rule of thirds. I'm sure you have heard of this, but if you've never learned about it, here is a link that explains the basic idea.
http://www.silverlight.co.uk/tutorials/compose_expose/thirds.html
Hope that helps a little. I'll let others chime in on posing/capturing the moment, as I can really think of how to critique it.