Depending on the airline, do the check-in online and print the boarding pass at home. With Delta we check-in online and also pay for the checked luggage at the same time. Once at the airport you can go to the kiosk (have to use the cc that the reservation was made with) and finish the luggage check-in by getting baggage claim printout, or go the the curbside desk and they will finish the luggage check for you.