Check with the appropriate consulate or embassy in your country to find out if you will need a visa to visit the country of your destination, especially for an extended period of time. Some countries have extremely detailed and complicated entry/departure laws, and treat visits of a week or two very differently from longer stays.
If you’re traveling to one area, check the cost of living there. If it’s high you’ll probably want to budget more carefully and save some money before leaving. The lower the cost of living the less you’ll have to save, but be sure to have a back up reserve in emergency cases.
Talk to other people who have done a similar trip.
If you don’t know anyone personally, try any of the dozens of online travel web sites full of first-person travel stories covering every possible type of trip.
* Plan big and loose. Read everything you can about the area.
* Set up a pre-trip time-line so you don’t end up with a full todo list your last week of work or school.
* The longer the trip, the lighter you should pack. This might seem strange, but it’s true you can afford to lug a heavy bag around for a week or two, but do you want to have anything extra for a year?
* Make contact with the locals before you go.
Maybe you have a friend-of-a-friend or a foreign exchange student from high school you remember, or just found a friend through a travel web site