Cinch the Bag.
Baggy, 1992: Shapeless floral-print dress; your boyfriend's oversized hoodie
Most of us have trouble making shapeless look chic. It's just so darned shapeless. The trick to updating the flower-covered sack look is give it shape without losing the relaxed, floral irony that said, beneath a floppy old knit hat, "I'm cute. Who cares?"
Just add a cinching accessory or layer that brings your curves into the equation. Belts, sashes (especially in interesting, contrasting fabrics), fitted vests and, if you're crafty, nipping in the waist with a pair of statement brooches can pretty easily pull off the update.
Baggy, revised: Knee-length, bold-print dress cinched with wide, black leather belt; shrunken denim jacket; statement necklace
Now, speaking of that black leather belt ...