I soak the keg in PBW and hot water; probably about a gallon. Give it a shake every time I walk by it, turn it upside down in my garage sink, etc for about 24 hours. Then push the PBW through my beer line. I then rinse the keg with clean water, then add about a quart or two of StarSan, shake, and then push that through my beer line. Then I store the keg and leave the line until the next batch.