[navcom]

Sunsets fall into the "high dynamic range" limitation category. Dynamic range is the range between the darkest and brightest spots in your scene. The human eye can distinguish roughly 20 stops of light while your camera can only see about 9 or so. This is why when you expose for the sky, the foreground goes black, and if you expose for the foreground, the sky washes out.

Your camera cannot reproduce the entire dynamic range that is present in a sunset scene as the range from the darkest to brightest spots is huge. To compensate, you need to use either a graduated neutral density filter or use HDR software techniques as fletch describes to "push back" the brightness of the sun so you get a more balanced dynamic range. This will also help tremendously with your color issues.

Once you get a more balanced dynamic range, the next step is to get a proper exposure. For most camera's, auto exposure will slightly overexpose the sky leaving it washed out. You need to over-ride the auto settings by either lowering your exposure compensation or use manual or aperture priority mode and then purposely set it to underexpose a bit. With a digital camera, it's easy to experiment during the sunset to find the right settings if you are not familiar with what to do.

Also, as fletch describes, white balance is another huge factor in getting proper sky colors. Personally I would not recommend using the daylight setting but use the shade setting instead. It produces a warmer tone and brings out those pinks and oranges present in a sunset. Or you can custom set it if you like. It will come down to personal preference. I shoot in RAW and set my white balance to shade...but since the image is in RAW format, I can easily change the white balance in post-processing if I find something that works better for a particular scene.

Hope that helps!