I want to get active in here. :3
In each of the art classes I've taken, there's been two very basic elements to drawing: line control, and composition. There's more complex elements like perspective and shading, but those two are at the very base.
Line control is something that just happens with practice, and goes away without practice even if you're a good artist! It's that muscle memory thing. Basically it's just your ability to draw the lines and shapes you want, smoothly, and not wobble by accident, or get odd shapes you're not trying to draw. The first book I had on drawing assumed line control would develop and started teaching with simple shapes, focusing on composition. Later classes actually had excercises for line control, including drawing long lines across a page trying to remain as straight as possible, and drawing circles, trying to end up as close to a perfect circle as possible.
Then there's composition. That's just your understanding of what things look like, and how to copy that onto paper. You'll notice as you draw more that you can start taking things apart with your eyes, seeing basic shapes inside them and how they fit together, almost like seeing the gears of a machine. It's kind of cool, it just happens gradually as you practice more. This too gets rusty without practice (as I have experienced repeatedly XD )
I sketched up an example page. This was pretty fun to do. It's not perfect, I'm not happy with the boxy-foxy, but the circles one is ok. And I've always enjoyed stacking cubes in strange arrangements. Especially when you switch up the perspective and create impossible geometry. :P
(http://www.dream-camera.com/images/drawpractice.png)
I'm still working on regaining skill myself. But with some simple tools, it gets easier. Plus it's fun to screw around with, like those simple little 2d physics games. :3
Using real references is awesome too. But when you can see simple shapes inside them, it's even better!
Hope this helps!