If you plan on installing any hooks or hangers from your garage ceiling, you must attach them to a stud beam to ensure that they are secure and preserve the overall architectural integrity of your garage. A stud is a sturdy support beam capable of bearing a larger load of weight than drywall, which fills in the gap spaces in between studs and is both thin and non-supportive. However, because you can't visibly see the studs in your garage ceiling, you need to rely on technology in order to locate them.
Use a Stud Finder
Stud finders are battery-operated devices that use a sonar-type system to determine the presence of objects through a thin surface like drywall. They are very easy to use and can be purchased at most hardware stores.
Tap on the Ceiling
Although it is by no means a surefire method of determining the location of a stud in your garage ceiling, plain drywall makes a hollow sound when struck lightly with a finger or knuckle, while drywall with a stud behind it has a deeper sound. You can use your fingers to check and attempt to locate a stud in your garage ceiling.
The most important step, however, is to confirm the location of that stud with your stud finder. Follow the operating instructions for the stud finder by holding it up against the ceiling and slowly running it in a straight line. Most stud finders make a sound when they have encountered a stud.