Well, first things first, don't wash the berries until you're ready to eat them. Excess moisture could cause them to spoil quicker. Start by removing the berries from the store-bought package. Discard any that are starting to look bad.
If you've got a large fridge with plenty of space, store them in a single layer on a paper towel lined cookie sheet or plate making sure that none of the berries touch. Don't have a lot of room in the fridge? Place them in a glass container with a lid. If you're lucky, they will stay fresh for up to a week!
What's your tried-and-tested technique for storing fresh strawberries?