Refrigerate fresh berries as soon as you get them home, either in a plastic pack or in a covered bowl or container, preferably with some ventilation.  We find that berries stored  in in the refrigerator in a container that has some ventilation will keep longer.  Do not wash them before storing, as moisture will hasten the decay process.     Wash your berries just before you start snacking, and eat them within 10 days.