One thing I love about traveling is the life lessons you learn.
Lesson #1: Always do things in group/pairs. When I was visiting Paris this past summer with my uncle, he left me to go up the Eiffel Tower alone because he's afraid of heights. We agreed on a meeting place, but for reasons of no importance to the story, he never showed up as I sat under the Tower for 2 hours (from midnight to 2am) alone in a strange city.
Lesson #2: ALWAYS take a matchbook or business card from the hotel you're staying in, because if you need to remember the name/address/phone number, you'll have it. If you're lost, most hotels will direct you back or send out a taxi to your exact location. That is something I overlooked, and when I was wandering aimlessly through Paris at 2am, I could've really used some direction and help.
Lesson #3: Bring a bilingual dictionary. I tried to get help from police officers and others around me, but not as many people speak English as we think. At that point, I would've killed for a French-English dictionary.
Lesson #4: Carry a phone card made for the country you're in. I had a German phone card (I was in Germany the day before), and not surprisingly, it didn't work in France. I couldn't call my uncle's cell, his wife in Germany, nor my parents in the States. Sometimes it's great to feel like you're the only person in the world, but there is a place and a time for everything. This was neither the place nor the time for any of it. It was thanks to a Parisian man hitting on me and a Russian woman I met at the Tower that I slept somewhere that night, albeit her kitchen floor.
Lesson #5: This is more of a note to always remember--Parisian subways stop running from 1:30am to 6:30am on the weekends, something I discovered the hard way.
Lesson #6: Also a note, somehow, the phone number to a Parisian telephone booth will register on your caller ID in the states.
Lesson #7: Though it's summer, nights in northern France are chilly, and you'll need long pants and perhaps a really light jacket.
Lesson #8: Always, Always, ALWAYS pack light.