You can also do a volumetric taper if you don’t have an accurate milligram scale (and none of the ones on Amazon are accurate). Dissolve a larger, known amount of medicine in a known amount of water or propylene glycol, depending upon solubility of the medicine. Then dose the liquid by volume. For example, 1 gram of medicine in 1 liter of water = 1 mg per ml. You can easily dose even microgram amounts this way.