Locate the hinges on your gate. If it is a swing-type assembly, they will be where the the gate is attached permanently to the post or wall.
Grease the hinges by coating the moving mechanism with the grease, and allowing it to open and close a few times to work the grease into the moving parts. If needed, drop some oil on the top of the hinge where it can drip down through the assembly.
Locate the chain drive on sliding gates. Do so by checking with either your manual or the gate manufacturer or retailer.
Oil the chain thoroughly on a similar schedule to hinge maintenance.
Spray a silicon spray on the hinge or hinges of single-arm or “actuator” gates. This keeps them from freezing up during inclement weather.
Place mothballs into the control box of the gate to deter pests that might nest in or chew the wiring.
Blow out the remote controller periodically, if there is one, with compressed air, such as that purchased in cans for computer keyboard maintenance.
Clean the push-pull tube with a soft cloth monthly, and lubricate with a silicon spray on most models and brands of automatic gates.