All right let's just do this the easy way. Here are my commandments for pulling this trend off (Julie's rocking it already, Cat's recoiling in her old, ripped, dirty blue jeans.)
1. Keep them slim.
2. Keep the colors pop-y and clean.
3. Wear with neutral colored heels (or you'll look an extra from a bad 80s video).
4. Unless you're a masterful color-blocker, like Marc Jacobs and Dries Van Noten, keep your clothes neutral. Otherwise you run the risk of looking like a human flag or a pro athlete.
The "Don't Go There:" Refer to commandment number one.
Colored bell-bottoms are destined for the clearance rack. However, not to be a total curmudgeon -- when you do see them on your local sale rack, get 'em and cut them into shorts and wear them this summer. Done.