December would be a good time to explore Sri Lanka or Thailand. In case you have more than a week's time, you can also hop to Cambodia, Vietnam from Thailand.
Otherwise, you can also go for backpacking in East Europe, covering Croatia, Slovenia etc - for that, you need to apply for you Schengen Visa asap!
Enjoy!! Tips i make sure whenever I am leaving for an international trips: 1) Check the weather conditions 2) Make a list of places you need to visit 3) Pack less but efficient 4) Find out about the probable problems one could face eg. if city has a lots of crooks etc. 5) Make an itinerary and book hostels accordingly in advance to avoid problems there.
6) Try local food 7) Spend some time in local markets to get the 100% understanding of the local culture which helps a lot and gives you an amazing travel memory. P.S. point (4) helped me a lot when I went to Thailand, it almost saved me from getting crooked. Happy Traveling!!