Don’t forget to take copies of your birth cert, drivers lis, health card, and your plane tickets/confirmations too. Copy for you, copy left back home with a friend. I’ve never needed them for any of my trips, but I still do this as insurance. Only takes a minute, could make a big difference in certain circumstances.
And never forget rule number one: Keep your mouth shut in the shower!
Heh, that’s a good suggestion. Technology that didn’t even exist when I went backpacking through SE Asia! 
Edit: make sure if you store stuff online that it is really secure, I think.
When I travel, I always put my passport and ticket in a zippered pocket on whatever bag I carry and I always put them in the same pocket(s) every time. I make sure the pocket is zippered so nothing can fall out and I always use the same pocket(s) so that I can quickly determine if I have my essential items. I’m religious about this so that when I’m tired, or drunk, it’s still second nature to put the items in their proper place.
Don’t go crazy on overpacking. No one really packs for a three week trip, you pack for a one week trip and then do laundry. You’re staying with a friend who lives there, so you will have access to her facilities. If you’re not picky about brands, you can buy a lot of the toiletries when you get there, but don’t assume they’ll have the same ones that you are used to.
…A gentle reminder: Don’t marry anyone named Johnny while you’re there.