Frank Curkovic uploaded a tutorial where he has an amazing way for explaining the drawing with one point perspective. His explanations are presented in the tutorial. Also they are very simple and clear. The tutorial will give you the vision about drawing with this style and it will give you the basic instructions for beginners. He recommended to draw two intersecting lines over the paper, and then a small rectangle in the middle. After that, you should draw straight lines that come out from the dot where the two initial lines cut each other. These lines will serve you as a guidelines for all of the elements in the room.