Before you draw a boxand costs to identify the worksheet location of its location using the method-of-sight. Specify the lower and upper sides. Define the height of the edge that is closest to you and check it in. Then draw lines from the upper and lower points. Their slope define the position of the figure. If it is at eye level, the lines will be horizontal. If below eye level, the lines will be pointing up. Accordingly, if the figure is above eye level, the lines will be located downward angle.
If you draw a box properly, not mathematically, the lines are not perfectly parallel. They should converge in the long term, that is, if you extend the lines, they converge at a certain point. After a horizontal line the right one, measure their length by the method-of-sight and draw a vertical line. Thus, the side that is closer to us will be ready. To make sure the build is correct, spend as invisible to the eye side. If everything works correctly, then the bottom square is supposed to be more upper.
PI the figure is a boxand for the first time should recheck the correctness of all faces. If you are not familiar with the method of sight use the following tip. Take a pencil and place it at arm's length parallel to the eyes. The height should match the width of the boxes that you make rubbings. That is, measure the width and see how many times she placed in the top. Also note on your drawing. The same method can be used to measure compliance and near sides with the far. When you make sure that all sides built right, the job is finished. Of course, in the beginning you will need to use a ruler, but in the future it will be possible to do without it.