Attached Link: http://www.xn--rnskldsvik-dcbe.net/c3d/Vue6_render_settings.pdf

Here are some great tips for optimizing render settings.

Another thing that is not mentioned here and many people seem to neglect: the quality slider in the atmosphere settings has a huge impact in render time. Normally, you can put that slider in negative values (like -1, for example) with very little impact in the image quality.