1- She's an acquaintance you barely know and you've just seen her for the first time in a while - Hug?

2- What if this acquaintance has friends that you've never met before - Shake?

3- She's an acquaintance that you see every week - hug?

4- You walk into a party and see a girl you know.. you hug her and kiss her on the cheek.. then she introduces you to her friend - Shake or Kiss on the Cheek?

5- Meeting a girl for the first time - nice handshake?

6- Family functions and gatherings - the men shake hands and opposites kiss on the cheek?

Feel free to add any other particular noteworthy situations where one may be more appropriate than the other.