For domestic flights, ensure that you check in 2 hours before your flight time. For international flights you should check in 3 hours early. For either type of flights, make sure that you have all your documentation readily available. You will need your ticket, proper identification, and for international flights, your passport and, if required, your visa.
Don’t check in at the last minute. Even if you make the flight, your bag may not. If you miss the airline’s check-in deadline, the carrier might not assume liability for your bag if it is delayed or lost. If you have a choice, select flights that minimize the potential for baggage disruption. The likelihood of a bag going astray increases from #1 to #4 below (i.e., #1 is safest): 1) nonstop flight 2) direct or ‘through’ flight (one or more stops, but no change of aircraft) 3) online connection (change of aircraft but not airlines) 4) interline connection (change of aircraft and airlines)
Check with the airline on luggage weight restrictions. Different airlines and different classes of travel have different rules. Be prepared to pay for excess weight. When you check in, remove straps...