Unless your state/country has specific laws about how to store it, I would recommend watching Bob McBride’s (of Black Powder TV YouTube channel and this Forum) video on storing the holy black. I have mine in the original containers, in a wooden box (with a closed, but unfastened, lid) inside a bigger wooden chest (again, with a closed, but unfastened lid). Seems to work fine. YMMVI too like to buy bulk powder BUT, storing it tends to be a problem! where can a guy get an approved storage container?
Also, keep your primers, etc. stored somewhere else.