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

Mostly called by rank, E3 and below by their last name, E4 and up by their rank unless they are Officers and the answer is yes Sir or no Sir. My men called me sarge others would say Sargent

In the army, E-1 through E-3 you can just call them by their name, E-4 has the lateral promotion so if the soldiers is a corporal you you call them corporal, if they are a specialist you dont have to call them by their rank u less they are a team leader. E-5 and up is just sergeant until you hit sergeant major, then you have officers which is just sir/ma'am.

I know in my unit it’s normal to call someone by their first name, as long as you out rank them and it’s within your work center. But technically, you should address people by their rank or abbreviations. Master Sergeant or Sergeant, Chief Master Sergeant or Chief, etc...

I’ve always called em all by their rank, the only one I throw a “sir or ma’am” to is officers..

When they are going through training, as you did, it's a whole different world. As an E4, you greet those of other branches with the same respect you deserve.

I ark have people calling me Sir!! I tell that just because you’re my sons-in-law, you don’t have to call me sir. Chief is good

While in training Boots call Their NCOs Sir
Or ma’am... only then.

As an Air Force SNCO I preferred Master Sgt. In today's joint environment it's an excellent question.

You are hearing NCO's being called sir/ma'am in boot camp so they get used to the word sir or ma'am. In the fleet, you call E-7 Chief.

If I addressed my PSG as Sergeant, with him actually being a SFC. Ain’t no damn way I’d disrespect him by calling a marine of the same rank something different. My PSG deserves all the respect in the world and if he was fine with Sergeant then a gunny would have to deal with it too...