I’ve been trying for a long time to capture a water drop just as it, well, drops—and finally succeeded in this photo thanks to the magic of the Nikon wireless macro strobe kit, patience and fortitude, and good luck.
This may seem like an obvious thing to state, but the primary determinant of the appearance of a water drop photo is the light source used in the capture because the way the water drop looks depends on reflections within the drop. So using a flash on a water drop does stop the motion of the water drop, both its falling motion (as in this photo) and other movement like that caused by the wind and surface disturbances.
But the bad news is that you won’t get what you see (which is unlike natural light water drop reflections, where pretty much you know what the drop looks like). Sometimes if you are very lucky the resulting photo will be an interesting or beautiful image (like the strobe-generated reflection in the water drop below), but it will always be an artificial construct created with the magic of a flash of light.