Any dry, temperature-stable place is good.
If there is likelihood that your container may be jostled, a double layer of cardboard will provide some extra protection.
I prefer to buy primers in boxes of 5000, and I just store them in that original box. Mark the date on the box so you can be sure to rotate your stock.
Powder always remains in its original container, except that when I open an 8# jug, I break it down into smaller 2# bottles, with appropriate labels containing type, lot number, and date of purchase. The big 8# jug takes up too much space on the loading bench, and is clumsy for pouring into the hopper of the powder measure. The smaller jugs also allow me to better monitor the rate of consumption of the original 8# jug.
Your local fire code will specify how much you can LEGALLY store in a residence.