Choose the course of your pathway. The pathway may be obvious, where pedestrians have trampled the grass, or you may choose a winding course toward a hidden nook. If a path is in a high-traffic area, don't vary far from the route; people tend to take the most direct route and will leave a winding pathway.
Walk the course with a normal gait. With each step, note the point where the center of your foot lands. Place a surveyor's flag, spot of spray paint or other marker at each point.
Remove the surveyor's flag as you place each flagstone. Center the flagstone on the marked point. Use the stone as a template and cut through the sod.
Move the stone aside and dig up the sod. Dig the site to the depth of the flagstone, then remove an additional inch of soil.
Add 1 inch of sand to the bottom of the hole. Set the stone back in the hole, adding or removing sand until the surface of the flagstone is at ground level. Tamp the flagstone firmly with the rubber mallet. Backfill any gaps between the flagstone and the surrounding lawn with soil.