I don't know much.
I'm just following this guy's recommendations....
http://www.pipedia.org/wiki/Pipe_Tobaccos#Aging
Q: So, I've opened an aged tin. Now what?
A: This is a little tricky. Once the seal of the tin is broken, the delicate balance present in that little ecosystem is permanently altered. You can't go back! So, once that tin is open, either smoke its contents fairly quickly, or transfer it to air-tight containers, like bail-top canning jars. The aging process from this point on will be different, but the tobacco will remain in fine condition for your enjoyment as long as it's kept in good condition. (The plastic lids on my tins will keep the tobacco in find shape for anywhere from a couple weeks to a few months, depending on the ambient temperature and humidity. Just keep an eye on it!) This is the reason, by the way, that I cellar 2-oz tins, rather than the 8-oz ones. Once I open that tin, I want to smoke its contents as quickly as possible to get the maximum enjoyment from my years of patience. It's like a fine wine - cellar it for a long time, but drink it fairly quickly.