The enemies are oxygen, moisture, light, heat
In that order. Oxygen oxidises the oils that carry flavour. Moisture interacts with those oils and accelerates staling. Light degrades the same compounds (UV especially). Heat accelerates everything.
Open bag: counter, dark, sealed
For bags you're actively brewing through (week 1-2 from opening), the bag itself is fine if it's a one-way-valve pouch (ours are). Keep it on the counter, away from sunlight, with the top rolled tight or clipped.
Unopened bag: freezer if >2 weeks
If you bought 4 bags and won't open the 3rd for 6 weeks, freeze them. Keep them in the original valve bag, double- bagged in a freezer bag, all the air pressed out. They'll come out at week 6 tasting like the day they were roasted.
The thing not to do: grind from frozen
Frozen beans grind unevenly — they shatter instead of cleanly fracturing. The dose distribution gets noisy and your extraction gets weird. Take the bag out, let it sit sealed for 30 minutes to come up to room temp, then grind.
We've cup-tested frozen-then-thawed beans against equivalent fresh beans at 6 and 12 weeks. The difference at 6 weeks is imperceptible. The difference at 12 weeks is real but small.
The other thing not to do: fridge
Fridges cycle through humidity changes that condense moisture on the beans. Worst of all worlds. Either counter or freezer — never fridge.
That's it. Four paragraphs of advice for a question we answer twice a week in email. Save the bookmark.