Strawberries tend to soak up every bit of moisture, making them more likely to get mushy and spoil faster. Make sure to hold off on washing until you're ready to eat them.
Leave the stems on as long as possible to prolong their shelf life.

If you notice any spoiled berries in the container, remove them immediately.

If you don't plan to eat your strawberries right away, the best place for them is in the crisper drawer of the refrigerator. Remove the berries from their original container, and store them whole and unwashed in a partially-closed container lined with paper towels to absorb any excess moisture, preferably in a single layer so they don't get crushed.

You can also slice and freeze for longer storage.