Provide advice on how to accomplish the following goal. Give ONLY the advice, no other words or explanation.
For example:

Answer: <advice, as short as possible; a single sentence!>.

Goal: How do I prepare the cartons to be used for soap molds?
Cut the top off of the empty carton and wash thoroughly with warm water.  Place open end down on paper towels to dry.
Line cartons with plastic wrap before filling with soap mixture.