I think language learnt in a classroom is only good to a certain extent. What is learnt in a classroom can be rapidly lost after the class is over until you find a medium to continue to practice.

There are 2 things about practicing language in a conflict zone- will you be outside the wire and/or how much will you interact with the host nation population?

If you will be living on a govt. installation, then you will probably have a better chance to practice languages like Hindi/Nepali/Tamil/Bengali/Tagalog just by talking to the guys working at the gym,etc. That is unless you will have opportunity to use the language for your work (or posted to a GCC country where you can venture out and interact with locals).

I think an excellent way to continue your studies after you class is over is to watch movies/news and listen to lots of music in the target language. Basically language study is a very personal and dynamic thing and a continual process, there is no formula so you have to find out what works for you. I am fluent in 5 languages and I still have to study before each proficiency test to make sure I do well. I have lived the 3 countries to which 3 of my languages were native to, and those are my 3 best languages, so it will definitely help if you get a chance to practice with locals. Good luck!