A long, blunt 16 gauge needle seems to work best. Put the needle on the syringe and clamp in a vertical position so that you can hang a drop from the end of the needle.  Shoot the laser at the hanging drop at a slight downward or horizontal angle which seems to work best.  Try to aim the laser into the middle of the drop so that the patterns can be seen as you move the laser from side to side (The needle end provides an interference of its own if you try to do this by moving the laser up and down).  The interference pattern will be reflected back to, and to the left or the right of the laser.  A white screen may used to make the pattern image sharper.  The interference pattern is produced by reflections from the front and back surfaces of the hanging drop.  Due to the distance between the surfaces and the curvature of the surfaces the pattern is produced.

An interesting side effect is that microscopic particles and contaminants in the drop are also visible.  They show up as a floating, circular interference pattern, that looks much like the Michelson interference pattern that is shown in 6D40.10.  The curved surface of the drop acts as a magnifying lens.