1. Know your kid. That's the first rule of family vacations. Got a little mermaid who loves "Finding Nemo"? Try snorkeling. Extreme adventure-loving teen? Consider a zip line or helicopter tour. On the other hand, if you've got a claustrophobic kid, stay away from the submarine ride, and leave the museum tour for another vacation if you've got a toddler in tow.
2. Don't overdo it. You want to see as much of a port as you can in your short day, but you're limited by the attention span and energy level of your kids, especially the wee ones. Don't drag your adventure-loving teen on an all-day tour of ancient ruins unless you want your day ruined. Don't expect a toddler to take a long walking tour of a historic town. If you choose to sightsee with your tyke, bring a packable stroller as well as a carrier, in case of cobblestones or other stroller obstacles.
3. Club it. Many of today's family-friendly cruises keep kids clubs open in port. Find out beforehand what the hours are for your ship's kids club. On days when you're not tendering, consider doing a just morning activity together as a family and letting your little ones enjoy the activities at the kids club while Mom and Dad explore the port. This strategy becomes tougher on days when you have to tender ashore, meaning you take a small boat from ship to shore and vice-versa. This process can add significant time to getting on and off the ship.
Check out: Best Cruises for Families
4. Bring the comforts of home. Pack a favorite toy or security blanket and some comfort food. (For little kids, that would be a juice box and a snack.) In the oh-so-rare situation of a meltdown in port, they'll come in handy.
Check out: Do's and Don'ts for Cruising With a Baby and Family Cruise Gear 101
5. Charge up. You want your teens and tweens to unplug, but today's wired generation gets a charge out of its gadgets. If you're taking an hourlong bus ride, let them rest easy with their iPods or Game Boys, and they'll be up for the adventure once you arrive. Outlets can be limited in cabins, and, depending on the line, power strips might be a no-no. Bring along a solar charger to help you keep everything fully juiced.
6. Give teens their time. Teens want their space. Most parents do, too. Give everyone a break by balancing together time and alone time, and the whole family will probably have a better time. Knowing this, cruises are increasingly catering to the "too cool to hang out with their parents" teen crowd. For example, if you drop anchor at Disney's private island, Castaway Cay, let your kids hang out at the teen-only beach. Other cruise lines, such as Carnival, offer teen-only port excursions. No parents are allowed on these outings. Instead, adult staff from the ship accompany the kids.
Check out: Best Cruises for Teens
7. Try something new. It's one of the most fun parts of vacation. With a cruise you get to do it every time you sail into a new port. Here are some water sports you might want to dive into on a tropical cruise:
Snuba. Not ready for scuba, but want to dive into the fun? Kids as young as 8 can try this alternative, which hooks an airline to your mask, connected to an oxygen tank that floats above you.
Scuba. Even if you aren't certified, some excursions will allow you and your kids (generally ages 12 and older -- check at the time of booking) to try an introductory dive with an instructor. Some cruise lines, including Royal Caribbean, will arrange for you to get PADI certified to scuba dive on a cruise.
Standup Paddleboard. Maybe you'd enjoy getting in on this fitness craze, combining surfing and canoeing, where you stand on an oversized surfboard and glide along with a single blade paddle. Most outfitters require children to be at least 7 years old.
Surfing. Encourage your kids to make waves while trying out this rad sport. It's a particularly good choice if you're in Hawaii, the birthplace of surfing. There are no strict age requirements, and, although you can rent a board at surf shops and go it alone, testing the waters with an introductory lesson will likely result in a better experience. Email a surf shop in port ahead of time if you want to arrange a class.
Check out: Best Shore Excursions for Kids
8. Dress for adventure. Make sure you bring the right clothes. For example, some of the churches and historic buildings in Europe have certain dress codes. Places like the Vatican's Holy City and Sistine Chapel require covered shoulders and skirts or shorts that cover the knees. That goes for men, women and kids. Men are actually advised to wear pants, unless it's a very hot day. Small children in shorts might be allowed in, but that would be left up to the guard, so it's best for everyone to cover up. Comfortable shoes are a must, as well.
Check out: The Ultimate Guide to Packing for a Cruise
9. Take a taxi. Larger families might consider private car tours. It's often less expensive per person than paying for each individual shore excursion, and it allows families to do exactly what they want on their own schedules. To find the best car services, check out Cruise Critic's message boards for guide recommendations in different ports. If you're waiting until you get to port to choose a guide, chat in person with drivers at the cruise terminal when you arrive. Choose a driver who's friendly and speaks English, and be sure to agree on a fare before you hop in. Also make sure to research laws about car seats before you arrive.
Check out: First-Timer's Guide to Shore Excursions
10. Make planning a family affair. Prior to booking, research shore excursions together as a family so you can get a feel for everyone's interests. Find excursions that appeal to both parents and kids. Make reservations in advance, as some excursions fill up early, ask whether the cruise line offers any special pricing for kids on shore excursions.
Check out: Family Cruising Basics and Cruise Critic's Family Cruising page
--By Andrea Guthman, Cruise Critic contributor