1.
You've got your insurance sorted, sounds like an obvious one (and touch wood nothing would happen that you would need it). I've gotten myself in a few situations where having the insurance has been a lifesaver!!
2.
You've found some things to do when you're there. I never liked to completely plan my trips but knowing I was going to an event or booked into a hostel that was sociable for travellers always made it easier to make friends and gain new experiences!
3.
You've researched the country you're visiting if you're going abroad. I signed up to FCDO Travel Alerts and they were actually the reason I cancelled my Ski Trip in time to claim back my deposits just before the Lockdowns were announced (always better safe than sorry)