You don't want it to dry out. I store bulk in mason jars to keep the humidity at a constant humidity level. For open tins, I'll just leave them if I anticipate smoking the whole tin in a week or two, otherwise, I put them in zip top bags for up to a month or so. Any longer than that and I transfer to jars.
Having said that, pipe tobacco doesn't need the humidity level of cigar storage. As long as it's not dried out when you get, just try to maintain it as it comes. It's also more receptive to re-humidification than cigars are, so if it does dry out a bit it's not difficult to bring it back. It won't be as good as if it had never dried out, but it will usually still be close.