Draw a horizontal line lightly across the page. This represents the horizon and will later be shaded over.
Draw a series of horizontal lines at various heights above the horizon line. These represent roof tops of various buildings. Leave a space in between each rooftop.
Draw a series of vertical lines down the side of each rooftop. These vertical lines represent the sides of each building.
Connect the side of each building to the side of the building next to it, using horizontal lines. These horizontal lines represent more rooftops in the sky line. Draw these rooftops above the horizon you established in step 1.
Shade the bottom half of the skyline. Shade over the horizon line as you do so.
Draw a series of antennas on the top of some of the buildings, at random.