One of the best things you can do to be prepared is to mentally plan the actions you would need to take in an emergency. As part of this plan, count seat rows between you and at least two exits. If you have any questions about the safety procedures, ask the flight attendant. None of the injured had their seat belts fastened. Make sure their seat belt is secured snugly and low across the hips.
Most airlines restrict carry-on baggage to two pieces per passenger.
It's a good idea to put the heavier items under the seat. Heavy items and baggage with sharp corners can be hazardous. Some hazardous materials are restricted. Following is a partial list of common articles from the home, workplace, or garage which, because of their physical or chemical properties, can pose a danger when transported. The above list is not all-inclusive.