When a cup doesn't taste right, it's tempting to tweak everything at once—grind, ratio, temperature, pour speed. Resist that. Change one variable at a time. Otherwise, you won't know what helped or hurt.

For example, if your coffee tastes bitter today, first try grinding coarser. If that doesn't fix it, next try lowering the water temperature. Keep notes, and you'll know exactly what works for your taste.