
It's beginning to look a lot like Christmas!
Municipal trees shine brightly, botanic gardens and arboretums treat visitors to elaborate illuminated shows, shop windows glow, and neighborhoods glimmer. Festive, twinkling lights are an integral part of the holiday season.
Dyed-in-the-wool Scrooges probably aren't swayed, but for everyone else, all of that glorious electrical magic does indeed make spirits bright.
It's hard to resist reaching for the camera when admiring these scenes. Unfortunately, the resulting images are often disappointing - washed out and/or lacking vibrancy. These tips will help you translate what you're seeing with your eyes into successful images.
Twilight Zone
The contrast of bright holiday lights against the darkness of night looks spectacular, but the best time to photograph them is before the sky has lost all color. During twilight, details are still visible thanks to ambient light. As a result, your images will have more visual depth. Especially if you want to include the sky in the composition, some color overhead is far more interesting than flat black - especially if there are clouds. (Added bonus: you may score with some sunset color.)
Exposure is also easier during twilight since the contrast differential is less extreme.
In total, there's roughly 35 minutes from the time sun dips below the horizon until the sky goes black. There are three phases to twilight, beginning with civil - the brightest - followed by nautical twilight, and then astronomical twilight. The amount and quality of light changes rapidly during twilight. Start shooting as soon as the sun sets, keeping an eye on your meter, and make more exposures every few minutes. Each photo will have a slightly different vibe.
My sweet spot is typically during nautical twilight and into the first part of astronomical twilight, which limits me to a working window of about 20 minutes. You might prefer it a little lighter or darker.
Targeting twilight clearly limits how much you can accomplish in a given day; you won't have time to cover multiple locations. Don't forget morning, though. Many municipalities keep their lights on overnight. Be in position about an hour before the sun comes up for another opportunity to work during twilight. The phases will be reversed, but it'll appear to be very light the closer you get to sunrise: much more so (to your eyes) than at sunset. That's why I recommend giving yourself plenty of time in the morning.
If Andy Williams were singing about the most wonderful time of the day rather than the most wonderful time of the year, he'd be crooning about photographing Christmas lights at twilight.
That said, sometimes a black sky is unavoidable. Holiday light shows at botanic gardens, zoos, and arboretums typically don't open their doors until the sun is setting - or afterward. In that case, don't worry. You can still make good photographs past twilight.

Steady as She Goes
Unless you're at a venue that bans them (more on that in a minute), always use a tripod. Select a slow ISO - as low as you can. This will produce a higher quality image by keeping noise to a minimum, and it'll enable you to use longer shutter speeds. Especially if you want to create light trails or make moving objects "disappear," you have to be on a tripod because you'll need to be able to keep the shutter open.
If you want to render points of light (think streetlamps) as starbursts, a tripod is necessary because you must stop down to f/16 or f/18 to achieve this effect.
A tripod will also lend an assist if you're capturing LED lights, which are constantly cycling on and off. It's not visible to your eyes, but use too fast of a shutter and your camera will see it; some of the lights will appear to be "off" in the resulting photo. The solution is to select a shutter speed of 1/60 or slower.
Whenever you're on the tripod, use a cable release to avoid shake.
Don't despair if you're attending a light show where tripods are not allowed. This happened to me last year when I had to go handheld at a botanic garden. Not wanting to use a shutter speed of less than 1/125, I chose a higher ISO and a wider aperture, and stayed away from my zoom lens. The results were quite good. Lightroom took care of the additional noise which was inevitable because of the faster ISO.
Turn Off Auto Focus
As it gets darker, your camera might start to have trouble focusing on its own. Better for you to take over.
Easy Does it With Exposure
The darker it is, the easier is can be to make mistakes with exposure. These are really contrasty situations, after all. Instinctively you might want to bump up the exposure, but this can result in blowing out the lights.
Err on the side of underexposing.
Check what you're doing. It may take a few captures to get it right.
Composition Still Matters
As with anything you're shooting, framing is important. Simplify; avoid clutter. Eliminate distractions.
Have Fun
Once bitten by the bug, your holiday seasons may never be the same! It happened to me; I hope never to recover. :)