Which word describes the act of saying or doing the proper thing?

The term that describes the act of saying or doing the proper thing is "tactful." Being tactful involves sensitivity in dealing with others or with difficult issues. A tactful person understands social nuances and is able to communicate in a way that is considerate and appropriate to the context. This quality helps maintain harmony in interactions and often involves choosing words carefully to avoid offending or upsetting someone.

The other options do not convey the same meaning. For example, "unseemly" refers to behavior that is not appropriate or proper, which is the opposite of tactfulness. "Wily" describes someone who is clever, often in a deceptive way, and does not necessarily imply propriety. "Uniform" relates to consistency or sameness, which does not pertain to the act of saying or doing things appropriately in social contexts.