Consider the length of the flight. If it's a short flight, you can easily check most items and board lightly. However, if it is more than a couple of hours, you will want to make sure you bring things that will keep you entertained or occupied during the length of the flight.
Know the rules. Since 9/11, airline security in America, Canada and Europe has changed drastically. You may have thought it a no brainer to carry on a liter of water just a few years ago. Today, you are only allowed 3-oz. containers of any gel, formula or liquid. Not only that, but they must be contained in one (and only one) quart-sized bag. This bag must have a zip closure because fold-over baggies are against the rules.
Pick the right sized carry-on bag. A 14-by-9-by-24 inch bag (45 inches max) is the largest size carry-on bag most airlines will allow, plus your shoulder bag. Anything larger will have to be checked, so make sure you follow these guidelines to the T.
Pack the essentials. Pick up trial-sized toiletries at your local drug store. Toothpaste, toothbrush, deodorant and shampoo can all be purchased in the qualifying sizes. For long trips, a change of undergarments, in the event your luggage is lost or delayed, is a good idea to pack.
Keep all legal documents with you. It is never a good idea to check these documents with your other luggage. Keeping your legal papers with you will prevent any chances of identity theft or headaches with international travel should these items get lost with your luggage.
