Hey Chrystal, Good job working on the Loomis head. The thing I notice the most is that your lines do not wrap around the shape of the head. The skull is a 3D shape, so make sure you wrap the lines around it. I did a quick sketch to show you what I mean :)

I found myself making many of the errors that Stan talked about in his gesture videos before reading a suggestion by another user on the forums who mentioned skipping the timer and focusing on line economy. You could try re-watching Stan’s videos and then taking a pose and doing the bare minimum for lines. Circle for the head, single lines for the limbs, and then only a few lines for the important parts of the torso. Draw slowly and focus on making solid/flowing CSI lines. Try that for a few pages or sessions and then increase your amount of lines. Circle for the head, a line or two for the neck if needed, two strokes for each limb, and then more lines for the torso but still focusing on flow and staying away from only contour. Also, don’t be afraid of exaggerating the pose which is something I struggled with at first. Those are some things that have helped me recently.

Look around you: eye level varies wildly between individuals, race and gender...

You're not over-complicating: this is complicated stuff. Just like you can construct vanishing points for directions in the horizontal plane, you can do so in the vertical plane. For figure drawing, this becomes way too technical, and it is typically eye-balled...

Are you sure this is not linguistic confusion? Flat colors may also mean plain color, without nuances or gradients...

John, I've just thought of the Andrew Loomis books. The "Figure Drawing" and "Creative Illustration" ones have very good sections on the use of perspective in illustration.

If you draw from elbow and shoulder, not resting your hand on the paper, you will have a lot more freedom to keep an eye on your line.

To be able to construct a perfect square in perspective, you need to understand a little more perspective, so you can construct the vanishing points for the diagonals of the square. using a 'stationary point'. It goes too far to explain it here, but google is your friend. Let me know if you need help, and I will see if I can find some pointers.

Newsprint, A1. It's cheap, so you can make al the mistakes your need, and it's big so it helps you to use the biggest possible muscles, like shoulder and elbow.

The models of Andrews Cawrse are great, but quality comes at a price. http://www.anatomytools.com

Learn to construct your vanishing points for the various angles. Or, drawing from intuition, create an animation of a rotating object, which will make you 'feel' where things go wrong...

Make sure your vanishing points sit on the same horizon line, unless you are going for some wild Dutch angle...

Looking great, just make sure to include feet!

Be sure to include hands and feet, and to indicate viewing direction!

It varies wildly between individuals, so it is hard to say anything about it...

Slow down. Follow Loomis' head construction to the letter.

These are a good start. I suggest you draw 'through', like a wire frame, so don't just chop off one side, but also the other one, which is usually not visible. This helps to find the vertical middle line of the head, which I believe is your main problem for now. Also, consider drawing a little bigger, keeping your pencil sharp, to go for a cleaner construction.

I guess you have friends and family, and yourself, who can pose non-nude? You can make fun, by asking them do dress up in special costumes...

Slow down, no need to hurry, and when you're done drawing, put a fresh sheet on top and see where you can improve your lines...

I think that what we're seeing here is a sphere with three circles that cut it in two equal halves. The best way to approach this is to start with a cube, and then cut it in two, in three possible ways, and from there construct the circles (I will cook up an example today). Although this a good exercise, in practice most artists will simply eyeball this, and another good exercise is to tighten rubberbands around a sphere, like a tennis ball, and draw this as a model.