The perfect fit - your breasts sit comfortably in the cups, and the mid partition of your bra sits against your skin
Loose and baggy cups - try a smaller size
Bulging and mid partition lifting - try a larger size
The perfect fit - your bra straps should be comfortably tight and not be digging deeply in your skin
Falling off - make sure to tighten your straps so they don’t fall off your shoulders
Excessive digging in - loosen your straps so they feel comfortable on your shoulders
The perfect fit - the band should sit parallel and flat against your skin when on the loosest hook
Riding up - try a smaller size
Digging in - try a larger size to avoid the feeling of the band pinching in your skin