The straight up & down or rectangular figure is a dream for fashion designers as it is easy to make it look good especially when slim. The objective with this body line is to create curves by pulling the eye out at the bust line and above and out at the hip line and below; this will make the waist look smaller. Defining the empire waist is a good option as this will divert attention away from thicker waist.
Colour blocking is also a great option – (See picture). This will create the illusion of curves.