Perspective woes

So yesterday I got the itch to learn. What is something I'm not quite good at and need help? Perspective. In fact, I wanted to draw a military vehicle of sorts. Problem was simple: wheels.

So I went on my journey of looking up how to draw a perfect ellipse in perspective. Step 1: draw a perfect square..... Wha.... How do you do that? I dredged through the interwebs, art forums, even going so far to a few Art Center students to limited success. Finally I came across a really long-winded series of videos for one point perspective ( http://www.youtube.com/watch?v=sfDbXPPzo0c ).

For the sake of myself, and anyone that happens across this, I'd like to reinterpret the video with a quick image/walk through. Let me preface this in saying, using this in a piece or planning is WAY too much work, and very limited. My intention of using this is to check my eyeballing- ie. draw 10 eyeballed squares, check them with this method, correct accordingly.

1. Draw 2 horizantal lines perpendicular to one another. The top one is the horizon line(HL), bottom is the ground line(GL). For the purpose of the exercise, a portion of the GL will be the closest leg of the square in space.
2. Measure between the HL and GL and multiply the distance by 1.73* (photoshop users can just use rectangle marquee to select the gap, then in the height dimensions type 173%). Measure the new quantity from the horizonline, and mark, this will be your eye point (EP).
3. Start your square, draw a reasonable length near the vertical line we just drew and create the front leg, and converge the edges toward the VP.
4. From the EP, measure 45 degrees each way from the center (photoshop users can make a square, rotate it 45 degrees and mark both edges). Draw 2 lines outwards until you meet the HL, mark the convergent points.
5. Connect the 2 initial points of your square to the opposite Median point (MP). You really only need to do 1, but 2 will help to make sure your work is correct.
6. VOILA! connect where the last 2 lines converge with your vanishing square legs and you have your last leg.

*Admittedly, I'm not sure the significance of 1.73. If I were to guess it has something to do with treating the square as 2 triangles, being that the square root of 3 is 1.73 blah blah blah. It works.