the main trick in photographing xmas lights is to get the lab to print the
images down, they tend to average the whole scene, which contains a lot of
dark areas to a relatively few bright ones, so they will make the blacks a
washed out gray.

if digital you would want to meter or aim the sensor at an area near the
lights, so the lights will still blow out bright but leave enough detail in
the surrounds, if you can, walk up the some partially lit areas and lock an
exposure in.

best time to shoot is when there is still a bit of detail, late twilight
when the sky is deep purple, but you can still sorta see.  again you will
want to print the image down as all meters will want to get into the medium
gray tone.

tripod is essential.

don't use flash.

make use of your camera's white balance, read the windows that are lit by
tungsten bulbs and the windows, especially if there is cool Norman Rockwell
christmas tree visible, will be warm/neutral and the snow will be a burrrr
cold blue.

you could try and find some tungsten balanced film but for some reason I've
never understood, they don' sell any that fast.  Like who ever heard of a
really brightly lit scene with tungsten lights, duh.

oh, did I mention a tripod.

just to make sure, tripod.