Planning an international trip can seem like a daunting process. There is a lot of preparation and planning involved, but if you break it up and take it step by step it becomes easier to handle (and to not procrastinate).
1. Get a passport.
Because you can't go anywhere outside your country without one. Get one as early as possible too - sometimes getting a passport can take months.
2. Decide exactly where you want to go.
If you think, "I want to go to Asia this winter," it'll probably take you longer to plan your trip because you don't know exactly where in Asia you want to go. And there are a lot of countries in Asia. Do you want to take a big trip to China? Thailand? The Philippines? Central Asia (all the 'stans)? This is a good time to set a "SMART" goal for your trip.
3. Book your flights (or whatever transportation you're using).
Do this early instead of waiting 'till the last minute and paying double the amount (I know this from experience, unfortunately...).
4. Do some research on where you're going.
Read blogs, look at TripAdvisor, Yelp, etc. To be completely honest, I learned a TON of tips and tricks from blogs, TripAdvisor, and Yelp - more than I did from guidebooks. Though I wouldn't completely rule out guidebooks. They can be helpful too, as long as you read updated versions.
5. Book your accommodations.
Or be spontaneous and do it while you're there. Though if you do book it once you arrive, make sure there will be accommodation available (for example, many hotels and hostels are already sold out for Oktoberfest 2014 in Munich, since it's a huge event. Also, consider holidays as well).
Again, TripAdvisor is a great review resource for finding good accommodations.
6. Notify your bank that you'll be abroad.
So they don't freeze your credit cards.
7. Pack your bags.
Make sure you don't forget these items.
8. And go!
Enjoy your trip and have fun!