Shoe: Basics
By Rio

The key to drawing shoes on any foot is to determine the view (eye level, down view, etc.), what position they are, and what shoe the person is wearing. Below is a line of eye level feet in different positions. If you are uncertain how to draw the foot, check out the Feet tutorial.
Shoe Level View
The first row shows the most common feet positions from dead-on forward, quarter, and combination of forward & parallel, and quarter & parallel. Notice that the ankle height is high compared to the ground. This is great for drawing feet with heels. If you're going to draw feet with flat soles, just lower the level of the ankle compared to the ground.
Below it is a row of the same feet with shoes drawn on it. What you basically do is draw the foot outline, draw the shoe over it, and erase the foot outline. A closer example if shown below:
Shoe Steps
Views of the foot is not limited to eye level and can come from above. Here we have two other views generally drawn from an angle and straight down view. Shoe Other Views

Once you get the hang of these three factors, drawing any shoe is a cinch!