To make a good proportional image, you first need to start with a basic plan. Make sure you use a pencil that can easily be erased when doing this, and don't press too hard.

When drawing a face front on, first draw a circle (you can use a compass or stencil if you really want). The first line represents the centre of the face (so when doing three quarter views you can bend it appropriately. I'll go through that later). It's very important to make sure your image is symmetrical. 

Next, draw the eye line. This should be between half way and a third of the way up the face. Make sure it's horizontal (otherwise the eyes will end up wonky). You can then draw in the shape of the chin. Goten's still a kid, so his face is still rounded.

 

From here you can draw the eyes. Use the centre line to make sure the pupils are the same distance from the centre line. Next draw the outline of the eyes. If you have trouble getting them to look the same, then try putting another horizontal line to mark the top of the eyes. Remember to draw the bottom line as well as the arches.

 

Then go on to the nose. In Goten's case just draw a small rounded triangle on its side. The eyebrows are pretty straight forward, in this case just draw to arches that come to a point. If you have trouble with the mouth, then just draw it closed for now. I'll go over emotions later on. Remember to draw the lines under the eyes.
 

Go over the chin again and check to make sure it looks right with the rest of the face. Then draw in the outline of the ears (once again, draw them at the same height and size). They shouldn't reach higher than the top of the eyes do. Then draw Goten's fringe. Usually he has one main spike to the left of the centre, and more spikes around the sides. In most pictures he has four or five spikes in his fringe.