I've always been a big fan of jewelry, but my favorite thing about it is mixing and matching to make a unique look.  There really are no rules when it comes to stacking necklaces....just put on whatever feels right to you.  Find a few things that have different lengths and that work well together.  It's fun to play up your jewelry, especially around the holidays when you often times dress up more than usual.  Take a peek in your jewelry box and have some fun.  Again, no need to buy something new to create a fun look for the holidays.  Just layer a few of your favorite necklaces and voila, you're done!