Personally, I never hang drywall vertically. The butt joints should be staggered so that you don't have four intersected joints. This makes it a bit easier. Start by haning a four foot long piece on the top row followed by a full sheet. Then hang a full sheet at the beginning of the bottom row. This will stagger the butt joints about four feet apart. Remember to leave a 1 inch gap between the bottom sheet and the floor.