[Mister Moo]

I try to keep no more tins open than what I'll smoke in a month or so - that way it may dry out a bit but, mostly, only enough to make it improve. Beyond that the plastic-bag thingie works for a few weeks but, in my experience, I leave stuff in a baggie longer than I plan to and it turns to dust. Hard to beat those little glass jam-jars with rubber seals on the lid.

If you try to keep small amounts of tobacco moist with a water-soaked clay button or a (thin-thin) slice of apple you need to be careful not to over-moisten - it's easy to generate mold if you don't sweat the H2O details.