Lighting Installation Planning
As you plan your outdoor lighting, there are several considerations you need to keep in mind. Naturally, you want the scheme to be pleasant to the eye, but you want it to be functional as well. You should also give consideration to matters of safety and security, matters of economy, and matters of light pollution.
Look and Feel - You want your outdoor lighting to give you a well-defined, three dimensional sense of space. You can do this by brightly lighting the background and dimly lighting the middle. The foreground should be lit more brightly than the back but not as brightly as the middle. Consider also what aspect you would like to spotlight.
Function - You want your outdoor lighting to create a useable area. Decks, patios, paths, and steps should be lit so they can be safely navigated at night and so that guests can see each other as well as your yard.
Safety and Security - By lighting for function, you've already gone a long way to securing the safety of your guests. Remember to light ponds as well and even rocks and rough patches to alert the walker. Make sure your lamps have proper glare shields so that no one gets blinded. Avoid uplighting for the most part since that directs lights up into the eyes. If you are going to uplight, make sure the light goes up into a tree or against a wall. For security, consider where the shadows near the walls are and make sure they aren't sufficient to hide an intruder.
Economy - By following the cardinal rule (Don't over light) you'll be keeping your costs down as well. Properly shielded lamps will focus all their light in the right direction so the bulbs won't need to be as high wattage. Security lighting can be attached to motion detectors so it doesn't have to stay on all the time. In general, use the most efficient lamp available.
Light Pollution - Make sure you consider your neighbors. Sending a lot of light into the night sky can wash out the stars. Sending an errant beam of light at an angle can illuminate your neighbor's bedroom in addition to the shrub it's pointed at. At another angle, it can get in the eyes of motorists driving by. As much as possible, choose fixtures that direct their output toward the ground. This will put light where you want it without getting it where it will simply irritate you or your neighbors.