How do you replace drywall around a bathtub?

If you want to do a really good, lasting job, use concrete/fibre board (Green board) instead of drywall. It comes in 30x60 sheets, about the same cost as drywall, easy to work with , totally water resistant and Excellent for tiling. About 4-5 kinds available, Rona and HD each have 2-3 types.