QUICK CONTENTS:
1. A Standard Rectangle
2. Rectangles in Perspe...
3. Contour Lines
4. Exercises
The obvious first basic shape, is the rectangle. I, however, will use this name to refer to any shape that has four edges, to keep terminology simple.
A Standard Rectangle
Drawing a regular rectangle is simple. Draw two vertical lines next to each other, and two horizontal lines underneath each other, and voila. Again, the overshooting technique I taught you is useful to get smooth lines.

Rectangles in Perspective
But, how often do you see such perfect rectangles in real life? Not often. Only when you look at rectangular objects in perfect side view, you actually see a rectangle. If you look at objects from an angle, the shapes will be distorted, which we call foreshortening. The reason for this is simply that things that are further away seem smaller, even though the sides of the rectangle are essentially of the same size in (three dimensional space).
In a rectangle, the vertical lines are parallel to each other (they have the same direction), and the horizontal lines as well. Foreshortened rectangles have at least one pair of parallel lines moving towards each other, depending on the perspective you choose. Essentially, this means that the parts of the rectangle that are further away should be smaller.

Contour Lines
The first law of drawing talked about contour lines; the lines wrapping around an object that showcase the three-dimensional form. With rectangles, it might seem obvious that the contour lines are nothing more than even more parallel lines within the rectangle. In perspective, however, it’s difficult to establish direction and position of contour lines from the top of your head. To solve this, there is a method called dividing rectangles.
Simply put, the two main diagonals of any rectangle intersect at its centre point, and basically subdivide the rectangle into four smaller ones. With these you can perform the same technique until you have the precision you need. The best thing about it is that it works for any shape, even in perspective!
Exercises
The exercises for this are simple ones I recommend you try to do every day as a warm-up.
Any Rectangle
Draw rectangles at different sizes. Try to create a square once in a while. If you feel adventurous, try to draw rotated rectangles as well.
Perspective Rectangles
Draw a random foreshortened rectangle, and subdivide it once.
Houses
Draw houses or churches, just like you used to do when you were young (probably). Try to use subdivision and foreshortening to add windows or other details.