First you should plan how you are going to install the lights in a way that it will add to beauty of your garden or landscaping. Do not just install a light here and a light there. Make a proper plan that should focus the careful selection of the spots where lights are needed the most and also the number of lights needed for the project. Estimate total budget and then go ahead with implementation of the project. You should also give a consideration to the safety aspect of the lights during the day or the time when you are not around.
You first consider and try installation of lights that are lit with green energy resources such as solar or wind power. The market now has purpose-made solar energy lights and you can install them in the landscaping area. This will also help you serve the environment in a way, and make you feel proud to have contributed towards this genuine cause. You might also talk to a company or even a charity that works for the conservation of the natural resources and environment. They might be able to financially patronize your project or at least share some cost of it.
If you somehow are not able to arrange green energy lights for the landscaping area, then installation of low-energy lights or energy savers are the only option left. The option is not bad either, especially if the lights have a public welfare element. For example, if there is a passage through the landscaping, the lights will help people to find their way out at nights easily. So in a way you are contributing towards a genuine cause, providing solution which is otherwise not your responsibility. So any money spent on the project will be worth recognized.
If the landscaping area is shared by more than one house in your neighborhood, you can talk to people in other houses and come up with a project that is shared by all houses. This will reduce the per head cost of the project and also people can contribute towards its protection and safety. Sometimes the landscaping area if properly lit can serve as night-times small community gatherings, where people can spend some quality time together.