A garage door opener does its work quietly, which is why the owner's checks are easy to skip. Set a short routine, keep a log, and the unit will show you what it needs.
Test the safety reversal
Place a flat board on the floor under the closing door. Close the door with the opener. The door should reverse when it touches the board. Repeat this test every few months and after any change to the door or the opener settings. If the door does not reverse, stop using the opener and have it adjusted before you run it again.
Clean and align the sensors
Wipe the lenses of the photo-eye sensors on both sides of the opening. Check that the indicator lights match what the manual describes. Look at the mounting brackets. If one has moved, the beam path changes. A sensor that is out of line can stop the door from closing, which is the safety system doing its job.
Check the door balance
Disconnect the opener using the release cord, then lift the door by hand to about waist height. A balanced door stays where you leave it. If it drops or rises quickly, the spring tension needs attention. Spring work belongs to a trained technician, not the owner. Note what you saw in your log.
Lubricate and tighten what the manual names
Use the lubricant type the manual specifies on the rollers, hinges, and the chain or screw drive. Tighten the mounting bolts, the bracket screws, and the rail connections. Look for play in the trolley, and check the chain or belt for wear or fraying. Replace parts when the manual calls for it.
Keep a short log
Write down the date of each check, the reversal result, the balance result, and any parts or service visits. Keep the model number and the install year with the log. That record is what lets you plan the next step, whether that is a battery change or a conversation about replacement. For typical service life and planning, see Garage Door Opener: typical service life and when to plan.