As Calico said there are many ways to achieve this sort of look, some more realistic (or easier) than others. I would start by trying to roughly duplicate the real-life circumstances. Put the sun low on the horizon or even slightly below it, put any clouds in the sky that may have been present, adjust sunlight strength as necessary to get the right *amount* of light (also make sure you're using Global Illumination [GI] and probably settings of 2/2 for sample quality and relative detail respectively). Once you have the general lighting you can adjust colors. Try subtly changing the "blue sky horizon" or "haze" colours in the atmosphere for example. Small changes have a big effect though, and be sure to save your "before" scene just in case!
- Oshyan