Appliances
Besides lifestyle changes, like remembering to turn off lights, computers and the TV when you aren't using them, replacing appliances with more efficient ones is the easiest way to save energy. If you're already turning things off when not in use, more efficient appliances can make a sizable difference in your energy usage. The federal Department of Energy (DOE) manages the Energy-Star program, which sets maximum energy usage limits for various types of appliances. Manufactures then submit each model to be tested, and if it meets the standard, is allowed to carry the Energy-Star label. The Energy-Star program does not have standards for every type of appliance, and even when it does most manufacturers only have some models certified.
Anyone interested in "best in class" performance will want to look at the actual test data in more detail, since there can be a huge difference in energy use among the qualifying products. Those people seriously looking to reduce their energy use will also need to look at machines in each size class, since, for example, a qualifying 23Cu Ft refrigerator can use more energy than a qualifying 16Cu Ft one.
Aside from getting the most efficient devices, the best way to save energy is to have less devices and/or just use them less often. One big challenge is the issue of "Phantom loads", which is the energy a device uses when its not in use, which can easily add up to 50W and use over 1kwh per day in an average household, about as much as an efficient refigerator.
Likewise TVs left on all day use a lot of power. By comparison, blow driers, which draw a lot of power while they're running, don't use that much power in the big picture because they're not on for very long. A 1kw drier run for 6 minutes uses 1/10 of a kwh a day.
Each type of appliance has its own characteristics: the most significant ones are described below.
Refrigeration
Refrigerators have come a long way since the 1970s--so much so that ANY new refrigerator will be use at most half as much energy as a twenty year old one. A good Energy-Star one might only use a quarter of the energy as an older one. You can find all the qualifying models by going to http://www.energystar.gov/certified-products/detail/refrigerators. The best models in absolute energy use are the smaller ones--the larger models can use as much as 50% more energy than the smaller ones and still qualify. Although the amount of improvement has slowed, refrigerators continue to get more energy efficient. If vacuum panels ever become practical, refrigerators could become a low energy applianace.
Clothes washing/drying
Energy-Star qualified washers have gotten much more efficient, even since 2000. Newer models use less water in addition to reducing energy use. The difference between qualifying models can be significant, with the difference between the top model and the least qualifying one being around 30%.
Measuring the energy use of a washing machine is more complicated than with other appliances because you not only have to account for the electric the machine itself uses, but the energy used to heat the hot water it it uses, and the energy required to dry the clothes when its done. To further confuse the issue, the amount of energy used depends on the load size. Some new washers have the ability to adjust for the load size, rather than having you select it, reducing the hot water energy used on small loads. However, because the washer still has to run thru its entire cycle, it will use essentially the same amount of energy for a small load as it does for a large (depending on whether is also shortens the wash and spin cycles), so to get the full efficiency, you will have to fill the machine to its capacity.
Front loading (or machines that operate like them) use less water because they only use enough water to make the clothes soaked, not a whole barrel full. Many newer machines also have a very high spin speed which removes much more water from the clothes, allowing them to dry much faster--it takes less energy to squeeze water out by centrifugal force than by evaporative heat. Energy-star qualified machines are rated by their Modified Energy Factor (MEF), and Water Factor (WF). MEF takes into account the energy needed to run the machine as well as the resulting energy needed to dry the clothes (higher is better). WF is a measure of how much water the machine uses (lower is better). Both MEF & WF are adjusted for the capacity of the machine, so you can directly compare the two numbers regardless of machine capacity.
The conventional wisdom is that front loading machines make your clothes last longer because they don't use an agitator, and hence apply less force to the clothing (no actual references found).
Dryers all use about the same amount of energy, so Energy-Star doesn't rate them. The one feature that does make a difference is a moisture sensor (used in the "auto" cycle). Using the automatic cycle allows the dryer to shut off when the moisture in the exhaust air indicates the clothes are dry, whereas in a timed cycle, the dryer runs until the time runs out.
Dishwashers
Dishwashers are much more efficient than they used to be, generally using less water and energy to do their job. Since most of the energy used in a dishwasher is to heat the water and dishwashers use a fixed amount of water per cycle, its generally most efficient to only run the dishwasher when its full. Many dishwashers now come with a "soil sensor" the will eliminate wash cycles when the water running thru the machine starts being clear, making the "full dishwasher" rule not quite as critical (note: verify this).
Some machines can heat water themselves, which is an advantage for people who want to wash their dishes in very hot water. Without this, the only other option is to turn the thermostat on the hot water tank up, which causes it to have greater standby losses.
The 'heat dry' cycle often uses a significant amount of energy, and so by using 'air dry" instead, you will save energy. There is a sizeable difference between the top performing and minimally qualifying energy star models--as much as 50%.
Computers
Computers, especially desktop computers, use a lot of electric. As a rule of thumb, the more "powerful" high end models use more energy than the standard ones. Laptops, because they have to be able to operate on batteries use significantly less energy-- a desktop might use nearly 200 watts, while a laptop is more likely to use around 30. As most desktop users have migrated to using LCD monitors, the total energy used by the desktop has gone down, shrinking the gap a little, and since most desktop users have migrated to laptops, tablets or just smart phones, energy use by the device is less.
Another important feature is to use the energy saving software that powers down the monitor, hard drive as well as hibernating the machine when it hasn't been in use for a while. The sooner the machine hibernates the better, but obviously having the machine hibernate while your thinking or going on small break is very undesirable.
Resources
The energy star site: www.energystar.gov
The American council for an energy efficient economy consumer guide: http://aceee.org/consumerguide/index.htm