Mr. Negativity here... and I'm assuming you're using Adobe Photoshop. Everything else sucks.
A lot of your text-work is hard to read. Try to avoid dark on dark / light on light. In your case it seems to be dark on dark, but both are bad. Your character images just look like you printscreened the model viewer, cropped out whatever color, and just slapped them in. That's not enough; work with the dodge/burn tools, and try doing some nifty layering effects and you might turn out with something spiffy. Photoshop has some built-in filters and stuff, and although I used to use them you'll probably start to be able to mimic them on your own and even do better effects on your own.
Basic things you can do to make these better, assuming you still have the source files:
1) Use the burn and dodge tools
2) Blur at least the edges of the characters
3) Maybe do some kind of a glow effect on the text. I generally do this on two layers, but Photoshop does have a built-in way to do this
Good luck.
EDIT: Don't feel bad, though. I used to do some pretty crappy stuff like so:
But with some practice you can probably do better. One of my better sigs I would say is this one:
or
Drastic difference in awesomeness I would say. To be fair even the text in my first example is hard to read. It can be hard to deal with. You don't have to use all of my suggestions, either. My examples don't use any kind of a glow, but they make use of Illustrator's shadow stuff.