Feel good knowing you're leaving for your trip having taken precautionary measures to keep your safety and responsibilities all in check. With travel, the adage couldn't be more true - better safe than sorry. And nothing sucks more than being in a new place when something goes wrong there or at home, and not having a clue how to deal with it - or worse, knowing it was preventable.
Don't forget to do these things before leaving for vacation:
Mail hold or mail forwarding - Don't let mail and packages pile up on your doorstep. Instead of asking people to pick up mail for you while you're out, arrange a mail hold so you can pick it up at a local post office (it can be done just a couple days in advance). You can also arrange a forwarding service that sends it to another address, but it can cause annoying delivery issues after the fact.
Leave valuables somewhere safe - Maybe you're not comfortable traveling with your wedding rings (etc.) or don't want to wear them on an active trip, so leave them with a loved one, at home or in a safety security box.
Notify neighbors - We like to let our landlord and next door neighbors know we'll be out for the longer trips, in the event there's an emergency. They can also be more observant of suspicious behavior knowing there shouldn't be someone in/around our home during that time. Also let them know if someone is going to be in the house whether its to check in or stay a while.
Autopay bills - Most people do this already but its worth mentioning. Make sure its setup properly and confirm payments are scheduled.
Leave travel info with someone - I usually leave a loose itinerary with family so they can track us in case of an emergency. Here's an example of the Google Doc I share.
Notify your credit card companies - Usually there's a quick form online you can submit to tell them you'll be traveling so they don't flag the card for suspicious activity (which they may still do anyway)
Digitize important docs/cards - Things like ID, insurance cards, maps, passport, etc can be photographed from your phone and filed in a folder in your photos app, and additionally uploaded to Google Drive or Dropbox for hosting (should you lose your phone, etc).
Download entertainment - Download music, books, podcasts and movies while you have wifi, so you have it on the flight or in places service is unavailable. Netflix and Amazon Video allow downloads.
Backup your phone and data cards - If something happens, at the very least you don't want to lose data or photos from before the trip. Start a trip with as much available memory as possible. Delete backed up media, data and apps you won't need, and bring backup batteries and storage cards. The big culprit for hoarding space on iPhones is usually "Documents and Data", so check out this link for how to lighten the load.
Update software - This is usually a good idea (assuming the new update isn't a mess). Update native app and OS software to make sure you're running optimally (and you don't deal with annoying OS update alerts).
Roaming service - Confirm your roaming policy with your phone carrier, but its likely just international travel you need to worry about. You can add temporary international coverage to your plan or buy a SIM card locally and insert it into your phone (if it's unlocked). Don't dare pay int'l roaming ad hoc - a couple minutes on Instagram or Google maps can get super expensive.
Be prepared for emergencies - If you get into trouble or injured or need help, do you know who to call? Do you have insurance coverage and do you know where its accepted? Do your homework and sign up for traveler's insurance if you think its necessary. Notate the phone numbers for the US Consulate, police, medical insurers, etc. You can also register for free with the Smart Traveler Enrollment Program (STEP) so the US Embassy is aware of your travels and knows how to reach you in case of an emergency like a natural disaster or attack.
Clean your house - I hate coming home to a messy house, so I clean as much as possible before taking off. Other housekeeping items include arranging coverage on homestead responsibilities while you're out, whether its watering the plants, checking on the home, or other things that would otherwise be left alone.
Plan your cash withdrawal strategy - I prefer to pull cash from an ATM overseas before I leave the airport. You get the best exchange rate from what I can tell. Do research on what the common method of payment is at your destination(s), because that will impact how much cash to carry. For example, you will not need any cash in Iceland, but will probably mostly pay in cash throughout Italy. Try to carry the least amount of cash necessary, you can always withdraw cash incrementally as needed from train stations or airports throughout your travels.
Know what power outlet adapters you need - Power outlets vary country-to-country, even in Europe. Google search which outlet is used in the countries your visiting and buy the appropriate adapters (and converter if you're planning to bring electronics). They're very cheap on Amazon.
Have a laundry plan - If you're planning to pack light, you will need to do laundry on the road. I book Airbnb's that offer a washer, and most hotels should have facilities (but double check). In Europe, we've been lucky to have access to a dryer since most people air-dry clothes. It's better to know that ahead of time, so you don't wash heavy clothes like jeans the night before a departure, only to realize they need a couple days to dry out. Been there, done that.
Taking a few extra precautions can help ensure you've covered your bases, and give you the peace of mind to fully enjoy your adventure.