Before you start traveling, check how long your passport is still valid for. Many countries require that you have a minimum of 6 months left on your passport but that may vary.
If you’re going to be traveling for a few months, and your passport doesn’t have a great length of time left, consider whether it is worth renewing your passport early to save the hassle of trying to visit consulates while abroad. It will also avoid complications with printed visas and carrying multiple passports.
I know some passports, including American passports, have allocated pages for visas and once these pages are full you need to apply for a new one. Some other countries require you have a minimum amount of pages free in your passport in order for them to grant a visa so have check yours before you travel.