If you want to avoid high levels of stress, start preparing for your trip a few days before you actually leave. Whatever you are flying from one country to another in Europe, or from one continent to another, it is always good to plan things out! Have everything you want to bring with you packed up. Place your luggage by the door. Some airlines allow you to check in twenty-four hours prior to your flight, if you are flying with one of these, check in and print out your boarding pass (if it is an option). Gather up all of your travel documents (ie passport, boarding pass, additional ID, and some cash. Put these in your carry-on and put them by your luggage. This helped me with knowing the gate number, flight number, airline, etc. I usually kept my ticket and notebook together. You will not have to think to remember to do anything special because you have everything set aside and ready to go.
In addition to having your beloveds prepared, you need to be ready too! Traveling will wear you out, so it is important to get at least some sleep before your flight. If your flight is early, try to adjust your schedule a few days before, so you can get to bed early and get a good night's sleep. The night before your flight (if it's early) set more than one alarm. I am typically good at waking up to one alarm, but it is better to be safe than sorry-you do not want to miss your flight! A practice that I started was laying out my clothes the night before. Like I said before, if something does not go smoothly, all you have to do is hop into the clothes that you have all ready!
Have your transportation lined up the day prior to your flight. If you are taking a taxi, call a taxi service and tell them what airport and what time your flight is. They may have a good idea on what time to get you-you will probably want to give yourself two hours from your starting point (you can adjust this depending on how far you live from the airport).
After you have everything planned and ready to go, you can get a good rest knowing that all you have to do the next morning is wake up and go! This should really cut down on the stress you feel before you travel. You can make sure you have everything and will not forget important things because you have given yourself plenty of time to get your effects in order.
If you do all of these things, your stress level will be cut in half!