-You need a good balance of christmas lights and daylight. Try to take the pictures when it isn't totally dark out side but almost there. If you take the pics when its pitch black outside you'll get too much glare from the lights.
-Use a tripod
-shoot all in manual and try different exposures (you can't trust your cameras LCD)
-watch for hotspots or spots that all the white detail is gone. (like my palm trees) try to avoid that at all costs. Remember expose for the highlights, process for the shadows.
This is a picture I took for an invisible permeant LED lighting system company...
I don't have a wide angle lens right now so I had to make do with a 50mm prime and stitch several photo's together. If you can, try to fit everything in one frame.
40D + 70-200mm f/2.8L IS + 50mm f/1.8
Manfrotto 055CX3 + 496RC2