a tree in the concrete jungle

There's lots of movement in this image, I think these trees are good for that

I think you've got a pretty decent composition here, a nice crop and whatnot. You seem to be doing well there.

Without knowing what equipment and software you have available to you, it's hard to recomment too much, but I will anyway just in case

First of all, definately use a tripod if you have one. The movement in the tree is interesting, but with a tripod it will help to sharpen focus elsewhere.

Second, and this only applys if you have Photoshop or some other similar image editing software, there's a couple things I might try to add interest to this image. I'd mess around with the levels a bit, bring the shadows up a bit, and maybe increase color saturation some. You don't have a lot to work with in the sky here, but I think you could maybe bring out the reflection in the water a bit.

Overall though, a nice image, and I'd be interested to see what you can do with it if you do indeed have photoshop.

Good job, keep it up