Though local codes rarely govern deck lighting, it's a good idea to install sconces around doorways and small recessed lamps on stair risers to prevent accidents at night.
On this deck, the homeowners topped the railing posts with lanterns. Other ambient light options include spotlights, mounted in nearby trees or on an overhead pergola, and solar-powered deck lights, which are easy to install since they require no wiring.
If you do choose solar, be sure to go with a high-quality set - the mechanisms in cheaper brands necessitate replacement every five years or so, which makes them a not-so-green choice.