Okay, well, if you're in a rush and can't provide details, I guess I'll just have to give you a rush answer, by golly!
Shoot your subject to be a ghost against a black background, making sure no lighting for the subject spills onto the background. A period costume and makeup to show a stage of decomposition would be cool, too.
Then it becomes a simple matter of playing with curves, levels, color correction effects,multiple layers, blurring and s few blend modes to get the desired effect. You shouldn't even need garbage masks... but if you do, they'll be really easy to animate.
There you go.
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA