A lot of good advice in this thread.

I would definitely go to my doctor and ask for prescriptions for antibiotics to have on hand. OTC meds are also a must, especially for gastrointestinal discomfort.

If you don't have an American Express card, get one. If you do, make sure you know how to reach them if you get in a jam. Unlike the US Embassy or Consulate, they are a travel agency and so on. American Express Global Assist can help you solve problems. When I was in Paris (before smartphones and the Internet), I broke my glasses and called them. Within a few minutes they called back giving me the locations of nearby opticians who were open, spoke English and had one-hour service.

While you might not be able to pass as a native, try to blend in and not look like tourists. The more you stand out the more likely you are to be targeted for theft or robbery.

If you EDC a knife or a multitool make very sure that you're following local law.

Look into what it might cost if you accidentally or deliberately use your cellphone for voice, text or data while abroad. You may want to get a local SIM or a local cellphone while you're there.