We know you were probably busy running around doing last-minute errands, packing (and re-packing) your bags when you thought, “I’ll just wait to get a manicure/pedicure until I’m onboard.” Not so fast. It’s not that you’ll get a sub-par manicure or pedicure in a cruise ship’s spa, it’s just that the same basic pampering that costs you $30-$40 back home will likely double or even triple. Some of the highest prices we’ve seen are in the Canyon Ranch SpaClub on Cunard’s Queen Mary 2, where manicure prices range from $48 to $101 and a pedicure will set you back $79 to $135.

The ship’s photo team usually sets up shop on formal night in heavy-traffic public spaces with lights and tropical or ocean-themed backdrops. It’s all free — to have your photo taken, that is. Then, you can opt to buy a package of 10 to 30 or more images for anywhere from $79 to $249. And if you want all the digital images along with your selected prints, that’s an additional $20. To save money (and ditch the backdrop — face it, most are hokey), ask a camera-savvy fellow passenger to snap an image and your formal portrait really will be free.

It's easy to get drawn to sparkly things in the display window when you're on vacation. Before you know it, you are the proud owner of a $3,000 watch or a $5,000 diamond bracelet. But will you feel the same as you disembark and realize the jewelry can’t be returned? Some cruisers have even reported that their purchases have been appraised for much less after the cruise. If you want a memento, stick with something lovely but inexpensive and save your big-ticket indulgences for reputable retailers back home.

The artwork in onboard galleries (most run by a single Michigan-based gallery) is often of debatable quality and value. Most passengers get sucked in during the onboard auction when passengers are wooed with free Champagne and then given a hard sell on why art is an investment. The trouble is that much of the offerings have inflated prices and some are of questionable authenticity. There have been lawsuits. Case closed.

If you’re the independent type who would rather trade organized shore excursions for exploring on your own, keep the following in mind: Many ships sail around 6pm — and if you’re in a major city on a Monday through Friday, that likely means traffic jams — so plan to explore the sights farthest from port first, and work your way back as the day progresses. If not, you'll find yourself too far away as all-aboard approaches, and you may even miss your ship.