I first started with
Artemisia absinthium. But you could take any plant you have around. A modern alchemist, from whom I learned the technique, said, that he tries out every possible plant he can find and test it on himself and on friends to find out which properties could be helpful. But
ATTENTION!
I am speaking here about tinctures, that are dissolved in a homeopathic manner. With direct tinctures, you need of course be very careful about toxic molecules inside. With a tincture, dissolved to 10 for example, there is little risk of intoxication.
I like the idea to use the plants, that are the most common around like Stinging nettle, Mugwort and after I have some personal preference for Cade and Myrtle.
Arthur Dee was one of the greatest alchemists of all time, not likely to his dad, I forgot his name, this small James Bond sorcerer working for the queen of a... Hail Arthur!