How do you personally greet a superior officer outside?

In uniform, I salute and verbally greet/acknowledge them.
Outside of uniform, I verbally greet/acknowledge them.

While it has been a while, much would depend upon how well I knew the officer and their rank. I know many will find this amazing, but I have been know to actually mess with people at various time in my military career? One of my favorite in connection to this question was the young lieutenant who I ran into coming out of those old WWII barracks, that had been converted into warehouses with a steaming cup of coffee in his right hand. I saluted out of reflex and the lieutenant came very close to throwing coffee into his own face, but caught himself just in time, quickly switched hands...spilling hot coffee all over his hand...and returned the salute. When I saw him switch the coffee back to his right hand...after that I just could not help myself. Told the corporal with me, 'Come on!' We sprinted around the building and we were able to get back in front of the good lieutenant just as he was turning to the short end of the building, offered another salute and greeting of the day, giant smile on my face as he sloshed coffee on his left hands again...the poor corporal having no idea what just happened but guilty by association...and I was surprised as well to find that the response to the greeting had been changed to variation of the F-bomb? My favorite part to this day is the confused look on the corporal's face and him realizing he had been messing with our new LT but not sure how he had been dragged into it.

I'm used to seeing Colonels and Sergeants Major frequently enough, outside of my own office. Salute, then greeting, salute is returned, carry on.

Though I did see one Major shout, "Don't salute me" to a group of Enlisted and Officers his junior returning from lunch in pairs. He was standing near the entrance, having a conversation with an SFC and I can only imagine that he had been getting a lot of salutes given where he was standing. So I informed him of a nearby bench where he wouldn't be bothered. Don't know if he took my suggestion, kind of his own fault really.