Any tips for international travel?

I am packing for a 20-day exchange program trip to Germany. I’ll be on an overnight flight and for 10 days I stay with my exchange partner and her family (she came here earlier this year) and then the next 10 days I am touring Germany and Switzerland. I plan on writing everything down so that I don’t forget anything… but I was wondering if anyone had some travel tips I could use?
Thanks.