For those of you who have traveled a lot, how were you able to afford it, especially if you were gone for months at a time?

I'm a military kid; one who has lived in Japan, Korea, and Hawaii to name a few places. My family has been living in Texas for the past 6 years and I'm starting to get very antsy; I want to go traveling. I graduate high school in a year and want to go on some big trip next summer after I graduate and I want to know the best ways to save money and how much I might need for a trip around Europe for a month.