Reducing an object to simple geometric shapes makes it far easier to draw the object. Once the basic shapes are established it becomes a simple case of judging angles and proportions. Oscar here was drawn around an oval.
By first fixing one or two key elements it becomes easy to see where everything else goes.
Usually you need to use more than one shape. I started this swan with a distorted rectangle and an oval.
Spaces form shapes too and drawing them as such helps to position other elements correctly.
By using simplification and a small amount of knowledge of facial proportions I was able to knock up this face in a couple of minutes without reference.
If you're totally new to drawing, try some simple shapes like these.
OK I cheated with the tree, I used Gimp Paint Studio tree foliage but you get the idea.