Wow, a lot of people like Japanese here it seems. I did the whole exchangestudent gig in 2002 (my last year of highschool). I learned a lot, not only the language but also about the culture. I went back and lived there for a time afterwards as well.
I would say that the best tip on learning a new language is to get yourself a girl-/boyfriend (whichever applies for you) and ask them to help you. This might not be a viable option if you already have one though.
I also read this book about memory (your memory by Kenneth L.Higbee) where the author briefly touches upon learning/remembering foreign phrases or words. By substituting words in the phrase with similar words in your own language, it's easier to remember.
Recently during a short trip to Iceland I tired this to learn a few phrases. Like "Orkestura flottur rass". I still don't know the correct spelling for this, but I remembered it by picking these words: Orkester, flott, (bacardi) razz. In Swedish (my native tongue) Orkester means Orchestra, flott means grease and bacardi razz is the same (a drink). Then I put this into a sentence like "Orkestern är flottig med Bacardi Razz" (The Orchestra is greasy with Bacardi Razz). It doesn't have to make any sense, in fact that is partly the idea. The more outrageous, the easier it will stick in your memory. So now I just work from that phrase backwards. Still remember it today, months afterwards.
What it meant? "You have a great ass". Sadly, I was recommended not to actually say this to any girls though. Wonder why...
