Well first thing I'm going to say is lower your f-stop number, and quickly read up on rule of the thirds. Also, set your shutter speed between 60-250 m/s. I also noticed that most of your shots are rather dark, so play around with the exposure settings too.
I'll be honest, you've really got the potential there, it shows in your photos you've already taken, you just need to find a style that suits your kind of photoshooting. Personally I like shooting at high aperture numbers i.e. 25-45, but when I go for that impression of speed, I like to use 4.5-8.0 and panning mode 3. That's another you should experiment with. Panning modes. They can really help make your photo sharper.
Last thing I'd say to help you is, when shooting standards, always capture at 2.0 magnification. That way when you resize them, you don't get the jaggy shadows as they are more faded out, etc. And just before I forget, when posting photos from Flickr, use the Medium 640 option as that's the perfect size for GTP, and it helps save peoples bandwidth too. Also loads faster ^_^
- BkS.