First, let's establish the why. Why a tincture instead of some other preparation? As mentioned in a
previous post here the reasons do vary. In some cases the parts of the herb we want are alcohol soluble more than water soluble. In other cases, we are limiting exposure to (but not eliminating) unpleasant tastes.
In my own case, I'm afraid tinctures are often the only way I can store the medicine plants for future use. Ever more humid summers are meaning I have difficulty drying them, and so I resort more often now to tinctures, vinegars and oils. (I never use a dehydrator, I find them too hot.)