At the workplace, it's simple: shake, nod, smile. Congratulations: You're introduced. But in other cases, it starts to get awkward. A handshakes seems a bit formal and a hug seems like a bit much. Cheek kiss? OK — but how many? If you go for one, she goes for two, and you accidentally leave her nuzzling air, you'll have no choice but to kill yourself, spoiling the very social gathering you're there for in the first place.
THE RULE: Let's settle this once and for all: right-handed shake, left-arm shoulder pat, and a single left-cheek kiss. EVERY SINGLE TIME.