The next two steps should be done quickly to avoid smears that are too thick. By capillary action, a thin line of blood will spread along the edge of the spreader . Quickly drag the spreader along the entire lenght of the sample slide in one fluid motion. Note that the blood is being dragged by the spreader. If the correct amount of blood was used, and the technique was performed correctly, the smear should end before the end of the sample slide.
Air dry the sample slide.
Fix and stain the slide. Various methods may be used. Normally a commercial staining kit is utilized following the manufacturer's instructions.