For the most distinct stripes in your cocktail, pour the densest liquid first, working your way up to the least dense. In this recipe, the grenadine should stay on the bottom of the glass since it is heavier and thicker than the other two liquids. Or, if you want your layers to bleed into each other a little, pour the least dense liquid first, and as the denser liquid trickles to the bottom, the layers will combine a little.