Print your cruise confirmation, electronic tickets for flights and any other tickets or confirmations before leaving. Keep your passport in a safe, easily accessible place. Also bring photo copies of your passport in case it is lost or stolen; bring one set of photo copies with you and leave another set at home.
Check the forecast for your ports of call before leaving and also consult with your specific cruise line for the dress code on board. Pack one daytime outfit for each day of your cruise, in addition to a swimsuit, pajamas and outerwear. Nights tend to be chilly on the water, so a sweater is a good idea, even in the summer. Dinners tend to be slightly more formal, so leave shorts and jeans for daytime and bring business casual style attire such as dresses, khakis and polos for evening. Since most cruises have one or more formal nights, also bring an evening gown, tuxedo or suit. Don't forget workout clothes if you plan to take a fitness class on the ship or use the gym.
Comfortable walking shoes for touring European cities are a must. Bring a pair of dress shoes for formal nights and sandals or flip flops for the beach or pool. Don't forget a pair of socks for each day of your trip. Leave expensive or flashy jewelry at home and pack costume pieces with you. A lightweight pashmina shawl or scarf comes in handy for women on cool nights or for covering exposed shoulders when visiting churches. Bring a hat and sunglasses to cover up on sunny days.
Unless you are insistent on a specific brand, forgo shampoo and soap since these will be provided in your cabin. Pack travel-sized deodorant and toothpaste, along with a toothbrush and any other toiletries such as sunscreen, makeup or facial lotion. Remember that airlines restrict liquids and gels in carry-on bags, so pack your toiletries in your checked luggage or bring bottles that are three ounces or smaller on the flight to Europe. Don't forget prescription medications and any over the counter medications you need.
Bring a camera, extra batteries and memory card, along with a separate video camera if you need one. Also pack a European guidebook and a small phrase book if you're visiting non-English speaking countries. A small tote or day pack to bring on land excursions is useful to carry your camera, guidebook, sunscreen, water and other essentials. Stash a small, fold-up umbrella or poncho in your bag in case of nasty weather. Bring along an MP3 player, books, crossword puzzles and other tools to keep you entertained when relaxing at the pool or waiting at the airport.