Do the online check-in and print the paperwork (before you leave home).
When you arrive at MCO collect your luggage and follow the ground transportation signs to the car rental area.
Take the paperwork out to the garage and pick your car (keys are in the cars).
Drive to the exit gate.
Hand the attendant your paperwork, credit card and drivers licence.
The attendant will check you out and you are on your way.
If you forget or can't check-in online, you can use the Kiosks near the
Alamo counter to check-in and avoid the line at the counter.
Tip: make sure that you use the same credit card to check-in as you did when you made the reservation, if they don't match you will end up in the line at the counter. Happened to us a couple of years ago. Made our reservations several months out, in the mean time got a new credit card with a better rewards program. Tried to check-in at the kiosk but the kiosk gave an error and directed us to the counter. The rep at the counter very quickly realized that the issue was the different credit card and he changed it with no problem, but it had cost us a 30 minute wait in the line.