#3 in our Summer Of Organized Travel is the itinerary.
-Flight numbers and times
-Phone numbers of rental car companies airlines, and hotels
-Addresses of hotels and any place you plan to visit
-When out of the country, the address and phone number of your country's embassy
It sounds really old school when I suggest that you write the times and numbers of your flights and hotels on an index card that you keep in your backpack or jacket. Having all of this written down will save you from wondering where you're supposed to be and how you're getting there, especially if your phone runs out of battery.
Thanks to The Spruce Blog for the awesome tips.