You're taking a cruise, hitting all those wonderful ports that attracted you to the cruise you booked but have you thought about what you are going to do when you get there? Of course the cruise line will encourage you to book their shore excursions ahead of time and that's not a bad idea. Just be sure to do your homework before you choose your excursions.
Go over the excursion list, read the descriptions, then get to your browser and search engine and plug in the destination to see what there is to see in each port. You may find that you can do the excursion on your own for half the price. (Just remember that you will be responsible for getting back to the ship on time. If you are not with one of the ship's excursions, they will not wait for you. Instead they will leave you passport with the shore authority and wave goodbye to you as they pull out. You will be responsible to get to the next port on your own.)
Once you have either booked a cruise excursion through the ship or on your own, you might want to remember a few things as you begin your excursion. First up is to dress appropriately. I've seen it more than once. Someone who thought their strap on sandals were good for hiking and climbing on trails. Read the description of that excursion and forgo fashion for comfort and safety. And while your are reading be sure to note whether or not you are responsible for your own lunch or snack and plan a little pocket money to take care of it.
Don't take valuables with you. Flashy jewelry, expensive watches, unnecessary electronics only attract those elements of the community that spot and target tourists. You become a magnet for pickpockets and thieves. Leave the valuables in the safe in your stateroom.
It is unlikely that you will need your passport. Take a photo ID with you like a drivers license. If you are concerned that a problem would arise where you might need the passport, take a copy of it with you. It's always good to have one anyway in case your passport is lost or stolen. Many cruise ships keep your passport on file to make immigration go more smoothly in many ports so having a copy of your passport is just an all around good idea.
Another alert for thievery is pulling out a large wad of cash or opening your wallet to expose the fact you have a large amount of money. Don't take more money ashore than you think you will spend. And if it's going to be more than $50 you might want to use your credit card instead. If it's in a country with foreign currency, the best exchange rate will be used by your bank when it's processed.
The key is to travel as light as possible. Use a small backpack or shoulder bag that you can carry unencumbered but can hold a bottle of water, an umbrella or rain poncho, your camera, and small essentials you may need like sun block and a small bag of snacks. Being prepared isn't just a good scouting motto.