I don't know dogs think in the abstract to the point they try to figure out what your hand position means, unless they have been regularly hit or slapped.
When meeting an adult dog for the first time, I like to be sitting - a non threatening position, and let the dog come to me and sniff.
I used to own a German Shepherd that got his kicks running up to people he didn't know, and intimidating them by growling and barking, but not biting. I swear he would smile at the terrified reactions he got. The only thing he loved more was tennis balls.
When introducing him to someone new, I would have them sit on the couch with a tennis ball, and instruct them to say his name, then throw the ball. Max would come running into the room, all piss and vinegar, until he seen the tennis ball, then he would make instant friends.
Larry