I use a propelling pencil with soft 2B leads and solid graphite pencils (2B, 4B, 6B and 8B) rather than those old fashioned things made of wood that need constant sharpening. If you only have wooden pencils then get a couple sharpened before you start and round down the hypodermic point on a scrap of paper. Having to jump up in the middle of drawing to sharpen a pencil really breaks your concentration. You must have a kneadable eraser or putty eraser as they are sometimes called. If you don't know what a putty eraser is then go to an art shop and buy one. They are very cheap. To use one first warm it in your hand, while constantly squashing it, until it's soft and sticky. Form a point with the eraser and dab the point on the paper to erase pencil marks - don't try and rub out with it! Keep the putty eraser in your non-drawing hand. If you only have a normal eraser use a feather to brush away the bits instead of smudging your drawing with your hand. A clip board is ideal for holding the paper. Use a smooth piece of thick cardboard as backing. If you fasten your paper down to a desk then it's awkward to draw shaded lines at some angles because you can't turn the paper.

Before you start drawing first practise by drawing with your pencil just off the paper. This may sound crazy but you need to get into the mood. Concentrate on the details of what you are going to draw and go through the motions of drawing for a minute. There's nothing more off-putting than to draw the first pencil mark and then immediately have to erase it. Look at the photograph you are drawing every couple of seconds - yes, that often. If you don't then you will start making up a different, and wrong, picture. By constantly looking at the original picture you burn the detail into your memory. As well as constantly comparing the detail of your drawing with the original you also need to constantly check the overall composition. What's the use of two individually perfect eyes if they don't match. So, look at the photograph, draw on your paper, look at the whole thing and repeat.

Eyes are the essence of a portrait. If the eyes are wrong then the portrait is dead. Just look at the first horrible image. Removing the highlights from the eyes makes the drawing flat and lifeless. The eye isn't just a white disc with a grey ring surrounding a black spot in the middle. Take a look in the bathroom mirror and see how many highlights dance across your eyes' surfaces as you move. If you observe a twinkle on one side of the pupil you'll probably also notice that the area around it appears relatively dark whereas on the opposite side of the pupil the iris is lighter. So in your drawing use this principle. In the second image, there are two glints but the rule still holds since the iris is lighter on the opposite side of each. Also, notice that the pupil is a dark hole surrounded by the iris muscle that is striated with lines radiating out from the pupil.