Well well I see that everyone is too shy and doesn't want to be the first to share with us his country's customs....so I 'll start and I hope that it will get you going...........
Ok celebrating Christmas in Greece...hmmm let me think...
First of all the decoration. Yes it's true that nowdays we decorate a christmas tree too but as you all know that's a western european custom (I think

)....the original greek custom is to decorate a small boat (you see Greeks are very attached to the sea and we've been a seafaring nation for ages so...)
Presents : We don't exchange gifts on Christmas eve but on New Year's eve.....that means that our Santa Claus - in greek called Agios Vasilis (aka Saint Basil)- comes a week later than to the rest of the world hahahaha
Sweets : Aha! Our traditional sweets are "melomakarona", "kourabiedes", "diples" and of course the king of Christmas sweets......"Vasilopita". Mmmm I have to explain some things here......you see our "Agios Vasilis" really existed (many centuries ago). He was an extremely wealthy man and according to the legend, every year he used to make "pites" (pies) in which he used to put gold coins and then he shared it to the poors. Nowdays "vasilopita" is usually a cake in which we put a coin. Right after midnight on New Year's eve we cut in pieces the "vasilopita" and whoever get's the piece with the coin has good luck all year long (it's like a lucky charm).
Carols : Children in Greece sing the carols on Chistmas and New Year's day........they go from door to door and sing and people give them candy and money.
Oh yes! We give great importance to the first person that will get in our house the very first day of the year (1st January). It must be a person that we consider as "gourlis" (aka luck-bringer). We give him an orange with a coin (hahaha coins everywhere) and money
Hmmmm I can't think of anything else now......
Come on everyone, don't be shy....please tell us how is Christmas in you country

There will come a time when you believe everything is finished. That will be the beginning.
--Louis L'Amour