A garage door opener install is a chain. The header bracket depends on the framing, the rail depends on the header, and the limit settings depend on the door moving freely by hand. Walk the job in that order and you will know at each step what is holding and what is not.
Start before the carton opens. Read the manual through once, find the model and serial plate on the motor unit, and write both in your planning folder. Then check the door itself. Lift it by hand slowly. It should rise and stop without a jerk, and the springs should be intact. If the door binds, the opener is not the fix. Spring and cable work belongs to a qualified door technician, not to the install.
Confirm the space. You need clear headroom above the door track, a clear run along the ceiling for the rail, and a sound spot for the header bracket. The header bracket should attach to solid framing, not to drywall or a loose ceiling board. Check the manual or ask the installer for the minimum headroom your model needs.
Check the power next. The outlet should be near the motor unit and on a circuit you can identify at the electrical panel. Mark that circuit in the panel now, while the labels are easy to read.
Then the mechanical order. Assemble the rail, lift the motor unit onto its ceiling bracket, fix the header bracket to framing, attach the trolley to the rail, and connect the door arm to the top of the door. Tighten each fastener as you go, not at the end. Loose hardware at the top of a door is the first thing to find when you come back.
Set the limits before you set the force. The open and closed limits tell the opener where the door stops. The force setting tells it how hard to push when something is in the way. Both are adjusted with the door and the opener running. Ask the installer to show you the adjustment points and to test the reverse function with a board on the floor before they leave.
Finish with the controls. Mount the wall control where small children cannot reach it and where you can see the door from it. Test the emergency release cord, and make sure it can be reached from the car side. Ask the installer to walk you through the release before anyone needs it in a hurry.
At close-out, ask four things. Which bracket was fixed to framing, and how was that checked. Who set the limits and the force, and to what settings. Where is the record of the model and serial. And what is the install year, so the planning date can be set from it. For the typical service life and how to turn the install year into a planning date, see the garage door opener page.