With my left hand, and I'd nail it as I've been doin it that way most of my life by accident any time someone tried to shake my hand

But in case tHIS sOcIeTy we LiVe iN forgot, I hate handshakes and would rather greet someone in a professional setting by booping their nose

Shake his left hand

(I’m sure there must be a hidden meaning in there somewhere.) I’d wait a second or two for him to act, then follow his lead.

I'd probably wait for him to see which hand he extends.

This reminded of one of my classmates when I was a master's student. He had a congenital disorder. His left hand was somewhat half-grown. There was no handshaking conundrum with him.

By saying "hello how are you" if you so wish

By shaking his left hand.

With his left hand.

Rub noses like the Inuit are said to do.

With my left hand ?

The Rimmer Salute

offer him the left