I use Google Docs. It's very simple but effective. In it, I have: * a packing checklist (peace of mind and helps you to not forget to pack certain things like

I use Google Docs. It's very simple but effective. In it, I have: * a packing checklist (peace of mind and helps you to not forget to pack certain things like pills, chargers, etc.), * daily outline of spots I want to hit (collected through a combination a Wikitravel and friends' recommendations) * important phone numbers (AirBnB hosts, emergency etc.), URLs to museum ticketing sites, admission ticket discount sites, etc. * a png of my passport. I also have a printed copy of said document in case my phone dies or whatever. I duplicate the doc the next trip, delete the irrelevant bits and add new relevant bits. Most other data stay the same. It's important for me to keep things simple and dynamic. I used to have more complicated systems, but simple lets you explore but still have peace of mind. Travel is a dynamic thing, and one has to allow for serendipity.