AUXMAN , CHAP 12 says:
"The Coast Guard is a maritime military service. The protocols and etiquette reflect the customs and traditions of the Naval/Sea Services as well as the military. The Auxiliary, as part of the Coast Guard family, must observe similar customs and protocols, even though Auxiliarists are civilians."
"....Since Auxiliarists wear a modified Coast Guard uniform, and an insignia of position, the requirements for courtesy and protocol are simplified and form the basis for an effective working relationship between Auxiliarists and Coast Guard personnel."
The hand salute is a long-established form of greeting and recognition exchanged between persons in the armed services. Saluting between Auxiliarists is not usually the custom. There may be occasions (when in uniform and covered) where courtesy and custom indicate that a salute is in order such as when returning a salute rendered by a member of the Armed Forces. It is also customary to exchange greetings such as “good morning,” “good afternoon,” “good evening,” etc. along with the salute. The exchange of greetings should also be accompanied by a smile or a cheerful expression.