I actually do both--I'll keep the tea in the bags they come in, but roll/fold down the tops tightly to keep out as much air as possible, and clip them shut with small binder clips. Then I stick them inside the glass jars (which are kept in a trunk away from light/heat/etc). Possibly a bit overzealous on my part, but it seems to work. The only problem is when I'm working with bigger bags of tea--4 oz or thereabouts--and then they don't fit so well into the jars. So they mostly just get the roll-and-clip treatment.