To get rid of the noise you’ll have to increase your skylight’s ‘Rays per sample value’. For fast renders I use something like 12-14 samples but it produces some noise. The default 20 is almost noiseless so that’s good for beauty renders.
Skylight alone looks very dull and boring. I personally like to set an omni light to cast some specular highlights and shadows to the objects in the scene. Orange omni light with dark blue shadows and a light blue skylight produces a typical daylight scene.
Check renderer > antialiasing > Filter settings for sharper image quality. I don’t know much about this stuff but I was told that Catmull-rom should produce pretty sharp renders. You might want to check the global supersampler settings aswell.
If you want really good renders you’ll have to use mental ray renderer with proper light calculations. There are some good tutorials for mental ray and the results can be pretty amazing.
However it can be a bit misleading to render game models with all the most advanced lighting setups since there are no game engines that could produce similar results.