First of all decide on the statement piece of your look. If it is a dress, then choose more delicate jewelry. If the evening attire is more modest, then you can wear more pieces of bijou. However do not forget that sometimes one breathtaking piece is all you need.
At all cost avoid wearing more than 2 pieces of bijou at a time. It will look too excessive. If you have a jewelry set, consisting of a bracelet, ring, necklace and earrings, follow the rule of thumb: earrings + ring, earrings + bracelet, or necklace+ ring.
Make also sure your accessories (clutch, shoes) are in line with the rest of your look. If they are your statement pieces, make sure you ditch the other bling.
Finally, always take into consideration your age, height, and the build, when you choose the jewelry. If you want to draw attention away from the neck area, look for longer necklaces. If your neck is wide, you can offset it by wearing graduated necklaces. Girls with a bony neck and chest should consider more multiple-strands necklaces.
To sum up, whatever you wear for your glamorous night out, make sure you feel comfortable and the proportions are right.
Enjoy your Christmas break and let me know what else would you add to this list!