1. Cutting it too close. You know what's worse than getting to the airport too early and having too much free time at the airport? Not arriving in time and missing your flight. Even if you cut it close and still make your flight, this is an unnecessarily stressful way to start any trip. Tip: Think about this differently. Come to the airport prepared with things to do, and use this as some uninterrupted time to enjoy yourself with your favorite book or game, or as a time to get some work done.
2. Overpacking. Very, very, very rarely do I hear people complaining about under packing. When they do wish they had brought something, nine times out of ten it is something they simply forgot, not something they decided not to bring. However, overpacking keeps you less organized, as you wade through things you don't need to find the one thing you do. Then, of course there is the extra weight you will be lugging around. All of this just adds stress, nothing more. But what is more stressful is that you will have less room in your bags to bring back things purchased abroad. Tip: Put everything you are thinking of packing on your bed, and then remove a third of it.
3. Failing to call your credit card companies to let them know you are traveling. You won't be buying much of anything (at least not with your credit cards) if you forget to notify your credit card companies of where you will be traveling. As soon as they see a purchase or two made abroad, they may suspend your card(s) and it can often be difficult and time consuming to call to get them opened again. Tip: This is easily avoidable by calling your credit card companies before you leave.
4. Relying too heavily on Internet pics and descriptions when deciding your vacation. It is common knowledge that the right camera angles and lighting can make virtually anything look radically different. Hotel rooms can look twice as large, and that view of the refinery can be blurred out. Food can photograph better than it tastes. Actors can be hired to look happy doing anything. Tip: Talk to a travel planner who has recently been to the destination and/or call the local tourism bureau.
5. Packing your essentials in checked baggage. Essential items are just that: essential. If you pack them in your checked luggage, and your luggage doesn't make the flight or goes missing, this could have devastating or even dangerous effects on your vacation. Tip: In addition to packing all medication in your carry-on bags, also pack a simple change of clothes and your favorite time-killer in your carry-on bag.
6. Traveling with negative people. Just because you are friends, doesn't mean you are good travel buddies. When you travel with others, you often spend a lot of uninterrupted time together and can be in unfamiliar, possibly stressful situations. You want to travel with someone who "gets" you, who travels with a "team" mentality, and is ideally as open to trying new things as you are. Tip: Before taking a long vacation with someone, start with a one or two night getaway and test the waters.
7. Depending too much on recommendations. Of course it is a good idea to check with friends and family about where to stay and things to do in your desired destination. However, sometimes we depend too much on these suggestions, and miss out on experiences or accommodations that are even better than what our friends experienced. They may say that you HAVE to go to XYZ restaurant or stay in XYZ hotel, like they did because they loved it. They may indeed know the best place, or they may not, and besides, this is your vacation, not theirs. Tip: Consult with several friends who have been there, and supplement this with your own research, such as what you might find from a Travel Agent, Trip Advisor, or elsewhere online.
8. Ignoring the flight. Some people research the place, hotel and tours they are going to experience but forget to research the means by which they will get there. Not only the airline, but also the type of plane, if there is a meal provided, if there is wifi onboard, etc. all can greatly impact your flight. Tip: Before flying, get on the airline website and look up what amenities are offered on the plane you will be flying. Find out what meal service, movies, beverages are included on a complimentary or paid basis. That way you will be prepared.
9. Forgetting chargers or adapters at home. This is definitely the most common thing people forget to pack, and it can be one of the most impossible to replace or find when away. If you can't charge your camera or other necessary device, this can simply add to vacation stress. Tip: The earlier you pack, the less likely you are to forget anything, because in the days leading up to your trip, as you remember things, you simply place them in your bag. If you travel often, you may wish to consider buying extra chargers for the things you use most, and when you come back from a trip, don't unpack them, nor your adapter.
10. Making yourself too accessible. Vacations should be a time when you can truly get away from it all. Vacations can also help you find out how people back home (in the workplace and otherwise) can get by without you. However, if you make yourself too accessible, you'll never really find out, and you will keep coworkers, bosses, and employees forever dependent on you, and forever invading your break from it all. Tip: Provide the contact information of the hotels where you will be staying to loved ones and business associates, and with the strict caveat that you should only be contacted in cases of emergencies, and that you will have limited access to email and phone.