You have the menu, the strategy, the guest list -- the biggest variable left is your stress level, and stress has a funny way of making us morph into those beings (or other B-words) we don't want to be. Relax. Or you could just find yourself behaving like...
The Invisible Hostess
Having failed to start on time, or having decided to make complex, last-minute dishes, you're in the kitchen, alone, all night. Very bad. As is jumping up to start cleaning while your guests are still at the table eating dessert.
The Miserable Faultfinder
Do not tell everyone whats wrong with the food before they even pick up their spoons. "So no one thinks the soup's too salty?" Really, what can they say?
The Rueful Dreamer
You saw a great recipe for Thai-style noodles but couldn't get the lemongrass. You thought about tiramisu, but went with a trifle. Don't tell people what they could have been eating. Most guests will love spaghetti and meatballs, if you don't start raving about some lobster ravioli you saw on TV.
The Insufferable Uberchef
Speaking of lobster ravioli, if the dishes served are very exotic and the wines very fine, let the guests notice it themselves. No bombarding them with gourmet commentary.
It's a challenge to have people over when you and your husband/boyfriend are in the midst of a squabble, but it happens. No matter what, avoid carping at each other and rehashing any long-running arguments.