I clean the keg with hot water then it gets a hot PBW soak overnight. The keg then gets another hot rinse and a quart of starsan solution shaken up inside. I then purge the keg completely with CO₂… pulling the pressure relief valve multiple times to evacuate O₂. I store the keg pressurized with CO₂ until it’s ready to be filled. When ready to fill I just release the pressure and rack the beer into the CO₂ filled keg.