I'm a self taught artist. I learn from books, practice and other artists. This technique is inspired by Darman Angir from Indonesia. And the reference photo used is found on Flickr.

When you look at photos of buildings and see their vertical lines tilted, it usually means that photo was shot with the camera pointed upwards. Buildings at the edge of the photo usually have the verticals tilted at a greater angle.

If the camera is pointed forward perfectly, buildings would have straight verticals.

When you're sketching, you can use this knowledge to make your sketches more dynamic. Angled lines create some sort of tension and excitement. It will also make it appear that you're drawing the building while looking upwards.

If you already have some knowledge of sketching, you can make these minor adjustments easily. Follow these steps.

1. First is to place a vertical line in your sketch. It can be outside your paper but it's easier if you put it within.
2. For all the lines on the left and right of that vertical, their tops will tilt towards the vertical while their bottom away. Something like this / | \ because the vanishing point is at the top (in the sky).
3. The further away from the vertical, the more tilted the line will be. Generally speaking, don't tilt the lines too much or that will affect how convincing your sketch will be. Too much distortion is not nice.

Below are the sketches I've made for the video tutorial.