What is the proper way to address NCOs in different branches?

A Marine Gunnery Sergeant typically likes to be called Gunny. Other senior MC ranks like the full title, ie: Master Sergeant, Master Gunnery Sergeant. Army senior NCOs are called Sergeant until they make 1st Sergeant or Sergeant Major. Never address an Army NCO as Sarge. He was Beetle Bailey's NCOIC/Platoon Sergeant. Air Force differs by individual but most should be addressed by full rank until they tell you differently. Navy senior NCOs are Chief, Senior Chief and Master Chief.

NCO's are addressed by rank and name. For example, in the Army and USMC, an E-5 and E-6 would both be addressed as Sergeant, even though the E-6 is a Staff Sergeant. The only time I ever heard "Staff Sergeant" used was in a more formal setting or when a superior was upset with the SSG's performance. An Army E-7 is a Sgt. First Class, but addressed as Sergeant, whereas a Marine E-7 is a Gunnery Sergeant or Gunny.

Air Force ranks use Airman and Sergeant, although I have never been comfortable trying to figure out their Sergeant structure. Navy and Coast Guard - I haven't a clue; sometimes I wonder if they even use rank except for decorations. Honestly, though, there is a specific etiquette for each service; don't be afraid to ask. But outside of Boot Camp, the reference "Sir" applies to officers only.

By their rank.

My Marine rank is Cpl, I got it at my 25th month in Service. I was in the Air Wing. Things were much more lax than in the rest of the Marine Corps. Pretty much everyone was addressed by the first name or nickname, whether they were Pvt or SSgt. Everyone above SSgt was call by their rank.
Post Marine Corps, I served in the Air Force. I retired as a Senior Master Sgt. I was either addressed as Sgt, Senior or Sir by junior Airmen. Fellow Airmen that were SSgt and above and I had served with for many years; first name basis.

In marine Boot camp wheb the Drill instructors tell the recuirts something the answers is yes sir. or sir yes sir.

however a army e4 should refer to a Marine gunnery sgt as gunnery sgt or gunny.

While I was in the Navy (over 30 years ago), it was perfectly fine to refer to all Chief Petty Officers as "Chief" omitting their Rating. Alternatively, you could refer to them as Chief, Senior Chief, and Master Chief as applicable. All other Navy NCOs (E-4 thru E-6) could and generally would be addressed as "Petty Officer" without their Rating or specific Rank. Use of the specific Rank was generally reserved for more formal situations such as commendations, reviews, or discipline. Use of the Rating was not generally used very much. I.e., Petty Officer Lastname or just Petty Officer - used most often, Petty Officer 2nd Class Lastname - used rarely, Electronic Technician 2nd Class Lastname - almost never used outside of records.

In the Marines we called an E-7 Gunny and so on up the line. I do not know when the rank was created. During WW11 a Gunny was called a Gunnery Sargent, He was usually over a gun crew. On occasions he could be a mean bastard, that's according to my dad when he was in the Corps.The lower ranks always call the person by his rank and then his last name.

By the rank on their collar, but some marines that I met were offended when I didn’t call the Staff SGT even though I was a SFC and had to tell him to chill out I didn’t mean anything by it. Remember this was in the early 90s.

I've always had the question of what to call a Marine Corps Warrant Officer in conversation with that person. We use Mr and Chief in the Army, what about the USMC for WO1 (Mr in the Army) and beyond, (Chief in the Army).

Each service is so very unique, if you ever have the opportunity of working in a multinational organization it will get even more confusing. Germans, British, Turkish, and all the other countries use unique rank styles and titles. Nice to see that you are taking an interest so as to render the proper respect to these service memebers.

An E7 in the Marine Corp is known as Gunney. In the Army they are Sergeant. The other 2 services really don't matter because 1 is the chair force, and the other has 600 sailors go out to sea and 300 couples come back. Lol no I'm just kidding as it is common practice to pick on other branches, but to be honest I really don't know about the naval ranks or too sure about the Air Force either.

Gunny, Only the Recruit use's Sir or Mam.

Rank and name always works . I loved to hear Top by my Soldiers and Officers in my unit

You can never go wrong with rank and name

No first name for an Air Force NCO, its Sergeant ! One the fills the position of 1st Sergeant is addressed as First Sergeant. An E9 is either Chief or Command Chief if He fills that position. More recently Senior has been used for Senior Master Sergeant. A first name never make the program any time I was serving and never should. That is not a proper address at all, ever and that I would make very clear to anyone that did not understand that !

Similar in the navy all petty officers are called sir and saluted in boot camp.once graduated the honorific petty officer last name is used up to E-6 E-7to 9are chief senior chief and master chief last name optional except on formal ocasions

And when you retire or get out, all of us are Brothers/Sisters. Yet referring to ones rank still shows respect.

USN
E-4 through E-6 Address as Petty Officer so and so.
E-7 is Chief
E-8 is Senior Chief
E-9 is Master Chief

Until you learning them all, the following response as worked well for me;
“Excuses me Sir/ Ma’am/ Boss (I’m from the south, and my accent proves it)/ Superior, how do I address you?”

In Bootcamp, we call everyone Sir/Ma’am. Once graduating and becoming a Marine, we call enlisted personnel by their rank.