You can find various suggestions for Christmas light night photography.   I will share the method I used last year and post one image which might have been in the forum in 2008. ** If you have a working way to take these shots, please post for all of us to try.  Fair enough?**

I played with exposure and since the particular lens had vibration reduction went with shooting all on MANUAL,  1/6 sec,  F 5.6, 400 ISO.   I chose F5.6 since the lens is a zoom and at the long end the aperture is max at 5.6.  I did not want to have to change exposure when using wider angle shots and zoom shots.   With vib reduction, 1/6 sec was just barely ok.  When we go out tomorrow or the next day to take night light photos, I will likely use a higher ISO and gain a little speed.  A faster prime lens just does not give the versatile view of the zoom lens( which I wish was faster on the long end.)  Any decent results will be posted to the Happy Holiday thread.

Now, you can always go manual and up the speed by opening the aperture or upping the ISO or both to get even more speed.  For example, my 1/6sec would be 1/12 at 800 ISO and to move the aperture to F4.0 would move it up again to 1/24sec.    A tripod is a good idea but I used a car door window ledge as the support and it worked pretty well.

Try higher speed and larger aperture than I did and see what suits you. One thing I did not do from experience with bad shots was use AUTO.    You may do fine with an auto setting but I find manual to work much better once you settle on a workable combo of aperture, shutter speed and ISO("film" speed).