It's very difficult to recommend exposure settings... and for that reason I was going to recommend bracketing, such as John suggested above. In fact, sunrises and sunsets are one of the few times I bracket, because it's really difficult to come up with a "right" exposure. I use either full or 2/3 stop bracketing increments and take 3 to 5 shots, whenever time allows. I don't like to bracket due to all the extra shos and because I normally can come up with accurate enough exposure.... but sunrises and sunsets are an exception. a camera will want to massively under-expose, so generally I will do most of my bracketing to the + side. But, the earlier point about making silhouettes is a good one... and that might call for slight - side exposure.
Other suggestions:
Shoot RAW. That gives you much more latitude to make exposure corrections and other adjustments in post-processing, which are very likely to be needed. In addition to exposure... there often is veiling flare causing loss of contrast and reduced color saturation. Those can be corrected in post-processing, which is always better done from a RAW file, than from a JPEG.
Remove any and all filters from your lens and make sure your lens is clean. This is to minimize flare, some of which is possible in spite of all the precautions... But a filter and/or dust or smears on a lens will make matters worse. If you must use a filter (such as blowing sand or near splashing surf), be sure to use a high quality, multi-coated one to minimize image problems. Following image was deliberately shot with a circular polarizing filter, as a test:
Even with a very high quality, multi-coated filter, there as signiificant veiling flare and ghost flare artifacts caused by the filter. The image also was under-exposued. It took some post-processing work to recover contrast and color saturation, to retouch away the ghost flare issues (most of which aren't obvious at Internet resolution and sizes), and to fix some chromatic aberration....
In fact, the worst kind of filter to use when shooting directly at the sun is a multi-layer, such as the circular polarizer I used above. With additional glass/air boundaries of that type of filter, it's even more likely to cause additional flare problems than a filter using only a single layer or glass (such as a "protection"/UV or Neutral Density filter). But, further, a polarizer has maximum effect when the camera and lens are aimed 90 degrees from the light source. Pointing right at the light source is actually 0 degrees, where the filter will have almost no polarizing effect anyway. So it's doing no good, while doing harm in other ways. The image below was shot without any filter, for the above reasons...
I also didn't want a polarizer to reduce reflections off the wet sand and rocks in the above image. That's another consideration, since reflections will often be an inherent part of sunrise/sunset shots.
Experiment with different lenses and different apertures. Some lenses can produce a "star" effect around specular highlights such as the sun or reflections. Usually those are strongest and clearest at smaller apertures. The number of points on the star is determined by the number of blades in your lens aperture. For example 6-blade and 8-blade apertures will create a 6-point and 8-point star, respectively. For some reason I really don't fully understand, odd number of blades cause twice the number of points on a star... for example 5-blade, 7-blade and 9-blade apertures will create 10-point, 14-point and 18-point stars, respectively.
To have control over whether or not a star will appear in the image (if a lens will do it), as well as to control depth of field, I will usually use with aperture priority auto exposure or manual exposure (with or without Auto ISO). To me, the aperture is the most important consideration, for these types of shots. Sometimes a certain shutter speed is wanted, too, though.
Finally, things change fast so don't dawdle. Get your shots quickly! But also don't be too quick to pack up and leave. Often some of the best shots and and the most dramatic light occur immediately after the sun has set. The opposite is true for sunrises, get there early and be prepared for pre-dawn drama.
peterg wrote:
When taking sunsets, remember to look behind you where there may be other great photo opportunities.
I agree! Also be sure to look behind you, where some interesting things might be happening.