There are lots of bitters recipes on the internet and almost all give a bunch of ingredients and says to cover them with everclear or vodka and let them sit for 2-4 weeks. That does not make sense to me because you do not know which component made the difference, good or bad.
I make tinctures of all sorts of spices, roots, leaves, fruits, etc. and then mix them. The base of most commercial bittering bitters is gentian bark. I made a couple quarts of it and start there. My latest success is a mocha bitters and a bit of it on vanilla bean ice cream is killer!
It has gentian, coffee, cocoa, cinnamon, vanilla, licorice seed and root, brown sugar simple syrup, ginger, and fennel.
I made one for Christmas with all the expected Christmasy spices.
