Drawing one-point perspective is an easy skill to learn with impressive results. By following a few rules, you can easily create realistic depth while drawing both interior and exterior spaces. "One-point" means there is one vanishing point, or one spot on the horizon towards which all vertical lines converge, while the horizontal lines remain parallel. Think of looking down railroad tracks: as the tracks approach the horizon, the metal rails appear closer to one another until the edges appear to touch, while the wooden planks stay parallel. The spot where the edges touch, even if it is out of view, is the vanishing point.
The first step to drawing one-point perspective is to draw the horizon line and place the vanishing point. Sometimes the horizon and vanishing point aren't visible, like if you're drawing an interior space, but it's still important to know where they are.
Above is an example of a transparant box, but many of the objects you'll draw, such as buildings, will be opaque, like in the example below.Now that you have the basics, try adding more rectangles to the composition.
One of the most famous examples of one-point perspective is Leonardo Da Vinci's The Last Supper, 1494-1498. Notice how all of the lines converge towards Christ's head. Leonardo used the one-point perspective technique to give the interior space depth, but also to direct the viewer's eye towards an important part of the image.