Hi sivekr,
A lot depends upon how the assets are placed.
For example, a hard image (e.g a loco) will look "sharper" when placed against softer imagery, such as foliage, distant soft landscapes, clouds etc., rather than against another hard image, such as a factory. It's the contrast between the objects that makes the brain think that the object is sharper.
Another trick is to place foreground objects to give a similar contrast, and also an increase in depth to the picture.
You can also change time of day in Surveyor/World. This can dramatically increase or decrease the clarity of an object - particularly the shiny bits, such as rails, wheel rims etc.  This tends to be more obvious on the sunny side of the object. Just swing the clock hand round to see what happens.
Try changing two of the performance settings in the Surveyor menu as well. 
Moving the "good weather fog" slider to the right will give an increasing haze to the middle and far distance. That will make closer objects appear sharper.
The "gamma" slider will lighten or darken the image.
Once you have captured your image you could also use image software to sharpen, lighten, darken or otherwise manipulate the result. I personally don't, but it is an accepted practice.
Like JRT, I find that Print Screen pasted to MS Paint works just fine, and gives me all the tools I need for screenshot posting.
Cheers
Casper
