What should clients be advised to do after a perm besides waiting to wash their hair?

After a perm, it is essential to advise clients to avoid swimming in chlorine as chlorinated water can be harsh on chemically treated hair. Chlorine can strip away the perm's shape and moisture, leading to dryness and potential damage. This guidance helps in maintaining the integrity and longevity of the perm.

While other options may seem relevant in the context of hair care, they do not directly address the immediate post-perm precautions necessary for maintaining the health of the hair. For instance, coloring hair immediately after a perm can lead to further stress on the hair strands. Similarly, using heat tools daily can damage the newly styled curls or waves, and cutting hair short is not typically recommended right after a perm unless there are specific reasons for such a drastic change. Thus, advising against swimming in chlorine is a key recommendation for preserving a perm's desired results.