So, I don't suppose this is "advice". Just a reflection on my initial travels abroad (that didn't happen until I was in my forties). First of all - keep a mental list of the things that are different (from your usual home base), and the things that are the same. It might surprise you.
Second - I don't know if it was the state of mind I was in at the time, or a common effect of traveling to other countries, but I found my attitude toward "dumb laws" and social customs changed while I was there. I saw irrational legal requirements and the like, that would have infuriated me in own country, as mere curiosities. I guess I felt less responsibility for it, and thus less need to judge.
Anyway - I envy you on your "maiden voyage". Are you going to stay for a while? Are you doing mostly touristy things? I've always had the urge (that runs counter to my g/f's agenda) to try to get a feel for how ordinary people in another country live -- eg. I was usually more interested in going to a local strip mall, than the famous museum. Both are fun, but seeing how people go about their daily lives (and seeing the differences and similarities to our own routines) was always the most interesting to me.