To get this achievement craft three unique solutions in the Alchemy Tab in the Radial Menu accessed by holding down Right Trigger. To craft solutions you will need certain extracts made with three of different types of herb found throughout the world, the recipe for crafting the extracts will be unlocked upon harvesting an herb for the first time, not from buying them or scavenging already harvested herbs from settlements.
For the easiest/already unlocked recipes that I recommend you will need:
Healing Potion: Three Rouge's Cap (Found on Dead Goblins and in the Forest) & Three Mergrass (Found near water, especially near spawn)
Antidote: Three Mugwort (Found in the Forest and lying around in settlements) & Three Mergrass
Oil of Accuracy: Three Dagger root (Found in the Forest) & Any Salt (Either Mugwort or Rouge's Cap)
Naturally, you can make any unique assortment of three solutions this is just a suggestion of easy to make potions that should be unlocked by default.