We store bird seed in our garage in a plastic garbage can with a lid. This keeps squirrels and rodents out. You can put the bag itself in there with a scoop or empty the bag of bird seed into the container and keep a scoop with it.
Remember our bird friends by remembering this tip for thistle. When thistle seed (also called niger) gets wet, it cakes together and the birds can't get it out of the feeder.
I reuse plastic milk jugs with the end cut off to use as scoops for birdseed. I reuse plastic juice bottles to store the seed in.
All year long, we feed the wild birds outside, we buy our wild bird seed and black sunflower seed in 25 lb. and 50 lb.
I have just discovered how easy it is to fill my outdoor bird feeder by pouring it out of a large plastic 2 liter soft drink bottle.