Thaw the frozen puff pastry on the counter about 15 minutes. The pastry should be chilled but still pliable when you're ready to work with it. If the pastry gets too warm, the butter layers will flatten and the pastry won't puff as high when it bakes.
Store raspberries and blueberries in their original container or spread out in a dish or pan lined with paper towels. Raspberries are very fragile. Plan to use them within a day or so to avoid moldy berries.