Thanks to a federal lawsuit, colleges no longer standardize aid packages for students accepted at more than one school. Wait a day or so. Financial-aid offices are deluged with calls right after the letters go out. Call, but be prepared. Think out your game plan.
Share offers from other schools.
You may meet mixed results, but you have little to lose. Don't reveal too much. If you're a sure thing, the school has no incentive to sweeten its offer. Financial-aid officers don't like to admit that they're open to dickering, of course.