Simple Lines to Illustrate a Point
The Skyline.
Your sketch need not always be heavily detailed. Instead focus on the details in the area of the sketch that emphasizes the point you want to illustrate. In this illustration I wanted to show the effects of the Iconic Building on the skyline of Beijing. Good or unpleasant you be the judge.
Sketchingjourney's Blog 
Thanks:)
It’s instructive to see the shape of the building separately. I am struggling with a drawing of some complex shapes – I think I’ll take your advice and create the shapes separately – understand them, and then bring them together.
Warm Regards,
Shafali
After a while the process comes naturally.