A list of common occasions and what to wear for each. Click on the occasion for more advice and some suggestions.

Dinner Party: Gauge your outfit by the party. Given the number of variable, there's no one right anser, which can make things a bit tricky.
Cocktail Party: Cocktail dresses are always in style, but you have other options.

Job Interview: You can't go wrong with a suit, but in many fields it's not the only (or best) choice.
A Funeral or Wake: While your outfit doesn't have to be black; it does have to be respectful.

A Baptism, Bar Mitzvah or other religious ceremony: Honor the occasion in attire that is tasteful, not stuffy. Steer clear of anything low-cut or clingy, but also of anything overly serious when celebrating a happy milestone.
A Night at the Theater, Ballet or Opera: Once upon a time, these evenings out were considered a license to dress to the nines. Nowadays, you've got a pretty wide variety. Still, spiff it up!

A Good First Impression (a first date, meeing the in-laws, school functions): Dress true to your personality but this isn't the time to take risks.
A "Festive" Party: Get dolled up and have fun with it. There are lots of options, from slinky tops with dressy slacks to a dress in a bold color or print.