Push the contrast of your picture, decrease the gamma to keep the highlights high and not grey like a brightness will do. when you are happy, use a mult to blue everything and darken everything. Use a keylight to have a matte of the lights that you will have to bright back and glow with maybe a sparkle effect on top.
Thats the way, after it depend of your shot and what you want to do.
You will probably have to roto some area to fine tune
cheers
PS: have references !!!!