Five things you need to know before taking your international trip
Some good things to keep in mind...
1. Passport.
2. Do you need a visa?
3. The fine print of hotel/airline/tour/cruise/etc. cancellation policies and bookings.
4. Travel insurance
5. Baggage restrictions
With #1, it mentions ensuring it has 6 months of validity. I also suggest people ensure they have adequate pages, as some destinations require a full blank page...