Wall studs are typically 16 inches apart. In older model homes, they may be 24 inches apart. Using a stud finder can help to locate the studs.
Studs are found on each side of a window, and light switches and outlets are often attached to one side of a stud. Crown molding or chair rails are usually nailed to studs, so finding a nail in the trim should tell where the stud is. Once a stud is found, the next one can be found by measuring 16 inches across the wall. If the next stud is not found, the stud may be another 8 inches farther along the wall.