In the graphics settings set your anti aliasing on and depending on your graphics card drivers you may be able to go into your display settings and tweak your settings to make your graphics appear more natural.
Still the compression on the images seem to high, which means too much of the original image detail is lost. When you compress your image to be listed on the forum the target is 100K, play with different settings until your compressed image looks close to the original.
I hope thayt helps you out!

P.S. The concept behind your shots are great, just the technical aspects need perfection.