Techniques
Sunset and Sunrise

Equipment.
A tripod is pretty much necessary. True, there can be a lot of light around and you could handhold but I would still say take the tripod. The best colours often emerge as the sun is on the horizon and at this time light levels are low. Also useful are the graduated neutral density filters. For information on these essential pieces of every kitbag see here.
Shooting.
One of the keys to good sunrise/set shooting is planning ahead. It pays to have an idea of where you are going to go for the shots. It is very useful to know where the sun will rise or set. It does not rise in the east nor set in the west except on the equinox. In winter it rises in the south east and sets in the south west. In summer it rises in the north east and sets in the north west. The location also changes with latitude, with summer sunrise and set getting nearer due north as you go north until eventually you cross the Arctic Circle and the sun does not set. These general directions are good for most times but if more precision is needed then you can download or buy sunrise/set calculators which will give you the compass reading of sunrise/set from any latitude and any time of year.
It’s a really good idea to search out sunrise and sunset locations. You can do this in your own area very easily just by keeping an eye open. You probably spend a lot of time driving and walking around your own area and this is the time to be looking for locations. As soon as you see a good then look for where sunrise and set will be. Check for accessibility, interfering clutter like phone lines and the time needed to get there. If it looks a good spot then keep it in mind so that when the conditions look good you can go directly to the location and get shooting. If you start madly looking for a place when the light is already good then you will need really good luck to get what you want.
You can do this also when you are away from home. When you are on holiday it can be a frustration to spend parts of the day looking for locations, especially if you are with a non photo-friendly group. A lot of guesswork can be eliminated by using a map. Knowing where the sunrise or set will be means that you can combine your holiday activities with location scouting.
It also pays to get there ahead of time. This gives you time to set up and to wander about and see what else you can shoot, looking at other viewpoints, etc. Getting there early is important when you are shooting from a location that you have to walk to. If you arrive puffed out and hot after a race against time you are more likely to miss the good shots. I have always got my best results when I have had time to relax and absorb the scene, to react to the unfolding spectacle and think about my pictures. Being there early with a beer in your rucksack is the way forward.
When you are in place don’t forget to look behind you. Most of the action will be occurring where the sun is but occasionally the subjects illuminated by the setting or rising sun can be better than the sunrise/set itself. This is the case in the hills when the light on the hills is sensational.
Make sure also that you wait until the show is really over. As the light falls and your eyes get accustomed to the gloom you will see the colours on the horizon. They will be faint but can be amazing. Exposure times can be very long but the film/sensor will pick up colours that are superb. An example of this is this shot which was taken half an hour after the sunset, with an exposure time of 6 seconds.
Exposure should be for the brightest highlight. Or rather the second brightest highlight as the sun itself will usually be a burnt out disc. If the sun is in the shot then take the reading of the scene with the sun just out of the picture. With the exposure lock, or by entering the aperture and speed in Manual, reframe the shot and take it. Just to be sure its worth bracketing a half and a full stop under. The exception to this is when the sun has been reduced to a dull disk by the atmosphere. This is usually just a couple of minutes after sunrise or a couple of minutes before sunset. If this is the case the meter reading of the scene should work fine.