One of the things that I like about shooting sunsets (and I shoot a lot of them) is that you can tweak the drama scale just by changing the exposure a few stops. And because there is no right or wrong exposure for sunsets (or sunrises if you're one of those nutty morning people), you have a real wide latitude of what constitutes a "correct" exposure. In fact, with sunsets, the only perfect exposure is the one that you like the most.
Most of the time, the safest way to get an technically acceptable sunset exposure (one where you can see some foreground detail and also get good color in the sky) is to meter without the sun in the frame. Just point the lens away from the sun itself, use your camera's exposure-lock feature to hold that exposure and then refocus. You might find though that this somewhat middle-of-the-road safe exposure is too bland for your tastes. One way that you can intensify the drama is by taking your exposure reading from a brighter area of the sky; again you still don't want the sun itself, but if you expose for a brighter area, you'll get darker, more saturated colors.
In this shot, for example, I did take some shots with the lens pointing at the darker clouds in the upper right, but the sky was too washed out (because I was metering a dark area the camera tried to expose for a darker subject). But then I took some frames, including this one, where I metered for that bright area along the horizon. These exposures were about two-and-a-half stops less than the ones where I metered with the sky and it really enhanced the drama.
Tomorrow: Same sunset shot during the afterglow--it will blow you away.