Outdoor Landscape Lighting Design Principles
The basic principle of lighting design is simple. Don't overlight. Low light levels are often more pleasing and relaxing to the eye. Too much lighting gives a washed out effect and makes everything look two-dimensional.
Another closely related principle follows from this. Vary the amount of lighting you use. Although you shouldn't overlight, that doesn't mean you can't have any bright spots in your landscape. Just choose these bright spots carefully since they will be focal points in the overall design. Varying the lighting elsewhere will ensure that the whole landscape functions as a unit. The eye can take in the whole without every part of that whole demanding equal attention.
The basic rule is to light the background the brightest, foreground with less bright light, and the middle ground somewhat dimly.
Try to use many sources of light rather than just a few powerful ones. The result is more pleasing to look at and less productive of glare. It's easier to achieve balance and smooth transitions this way as well.
Vertical lights shining from above can also add to the three-dimensional effect. It has the added advantage of placing the fixtures where they can't be tripped over or bumped into.
Another practical principle is to use well lights in turf and spotlights or floodlights in planters. A well light in the planter may look nice, but placing lights underground increases the likelihood of difficult maintenance issues. In turf, on the other hand, underground maintenance issues are the price you pay for keeping lights out of harm's way. Use well lights in turf so they aren't constantly being nicked by the lawnmower.
Plan in advance for flexibility. You may want to move the lights later on. So run an extra few feet of cable out to them. When the bushes grow, or you decide the angle just looks wrong, you'll be glad to be able to pick the light up and replant it nearby.
On the technical side, select cable size and lamp wattage to produce a circuit with voltage between 10.5 and 12 volts. You should own a volt meter and know how to use it. Excess voltage will result in hot lamps with short lives. Too low voltage will produce weak lighting.
Remember also that you'll rarely want to remove lights from a circuit, but you'll often want to add. Your initial design shouldn't use more than 80% of a transformer's capacity. That gives you some room to change your mind and throw on an extra lamp or two.
For underwater applications you need to be especially careful. Make sure to use waterproof splice rather than ordinary electrical tape. This will keep the splices from corroding and performing poorly. Fiber optic cable is also a good way to avoid this problem.