Firstly, establish what scale you wish to use for your drawing, which face of the object you're drawing is going to face you, and where your vanishing point and the horizon line will be. We will use a scale of 1:50 for this example. The horizon line will probably be just under a third of the way up from the bottom of your artboard. The higher the horizon line, the higher up your point of view will appear to be. The vanishing point is then taken as being along the horizon line - usually the centre. You must then establish 2 more vanishing points (labeled as vanishing points 2 & 3) - usually on the side edges of the horizon line. You then need to mark out suitable increments along the bottom of your artboard area - for example, at a 1:50 scale you could use 2cm increments to represent 1m distances. You should set up your artboard so as the base line represents an exact number of increments, as shown in the diagram below.
This will be the ground level grid for your drawing, made up of perspective squares of your desired size appropriate to the scale you are using. For example, if you are using a 1:50 scale, then each square drawn back from your 2cm increments would represent 1 square meter. Draw radial lines back from the marked increments along the bottom of the page to the central vanishing point. Then, draw a diagonal line across from one of the vanishing points at the edge of your artboard to the bottom corner on the opposite side of the artboard.
The diagonal line is used to work out where the horizontal guidelines at your desired increments will be positioned so as to disappear towards the vanishing point. You must now draw a horizontal line across the page at each point where the diagonal line crosses one of the marked increment lines.
Finally, draw more radial lines from the central vanishing point to where the horizontal lines cut the edge of the artboard. You can also add more horizontal lines once you've done this where the new radial lines cut the diagonal.
You can then proceed to plan out your drawing using the grid you have drawn. You know that, in this example, each grid square represents 1 square meter. In order to work out how tall to make objects in your drawing, you will use the same incremental steps you used along the bottom of your artboard. You can work out the height from the front edge of your grid, and then draw a line back to the central vanishing point. If you then draw a line up from it's starting point on the ground plane up to where it meets this line, you know that the height is accurate. This is demonstrated below.