Answer:
You will need a clean piece of un-lined sketching paper (any white paper will do if you haven't a sketch pad); two (2) pencils, one HB (regular pencil) very well sharpened and if you have one a soft pencil (4B is my favourite) it needs to be sharp, but not too pointy. You will also need a good eraser, I like the white artist erasers but any kind designed for use with pencils will do; a pencil sharpener, a ruler and either a shading stub or a piece of white felt (it doesn't need to be very big 2 inches square is plenty).
Start by placing you paper on a firm flat surface with the shorter sides top and bottom. Using your ruler, find the center of the paper - draw one light line from top to bottom, in the middle of the page, then draw another very light line from one side to the other, also in the middle of the page (your paper should now be divided into four (4) equal sized spaces). Using the HB pencil, draw an egg shape (very lightly) in the middle of the page. This egg needs to be pretty big, as that will be the size of the head, remember to leave enough room around the edges to add ears and hair and a neck (maybe shoulders). If doesn't matter which way the egg sits when you draw it as long as the slightly pointy end is pointed down when you start putting in the features.
Now for the technical part, if the vertical line (the one going up and down) in the center of the page, is not in the center of the egg, erase the part inside the egg and redraw one that is in the middle. Remember to work with very light lines, this is just the beginning. Now, check and redraw if necessary the line that runs horizontally (from side to side) through the egg at the very center. The next step is to draw another horizontal line, half way between the pointy end of the egg (the chin) and the first horizontal line you drew. Almost done, you need to draw one more horizontal line, half way between the chin and the second horizontal line you drew. If you got this right, you should have an egg shape, with the pointy end down, that has one vertical line down the middle and three horizontal lines (one at the half way point, one at the one quarter point and the last one at the one eighth point as you move down the egg toward the chin).
Now for the fun part, you can start to draw a little bit darker, but don't push too hard yet, you may need to erase some things. The line in the middle is the center of the nose and you will need to decide how wide the nose is, you might want to look at a picture in a magazine for some ideas, just be sure the face you are working from is full front (looking straight at you). The horizontal line in the middle, is where the eyes go, so be sure the nose goes up far enough to curve into eyebrows, and it goes down to the second horizontal line. I find the easiest way to draw the end of the nose is to make a small downward curving line at the bottom, and then two more small cured lines, one on either side of the first curve to make the edge of the nostrils. This takes practice so don't expect to get it perfect the very first time.
Now go back up to the eyes, this is the important feature, if you get the eyes right, the whole drawing is more effective. Start with a round circle on either side of the nose, this is the iris (the coloured part of the eye), check to see they are the same distance from the center of the nose, they should be out wider than the bottom of the nose, and they should be level with one another. Then put a smaller circle in the center of the iris -this is the pupil (the black part). Once that is done you add the eye lid, it is a curved line that is about twice as wide as the iris, and gently curved, it usually crosses over the top part of the iris (unless the person you are drawing is very surprised). There is a similar curve at the bottom of the eye. The upper and lower curves will join exactly on the nose side of the eye, and the lower curve will come slightly under the upper one on the outside of the eye.
Next the mouth, line three is the center of the mouth, and the lips go above and below that line. The mouth is wider than the nose and the the outside corners line up with the inside edge of the iris. In women the upper lip is often more curved and the lower lip is more rounded. Men generally have smaller upper lips and their lower lip is more like a shallow curve.
Now for the 4B pencil, using the side of the lead, add shadowing to your face, this is what makes it look three dimensional, so take your time, add a bit at a time and use the felt to blend it in (use curved strokes to give the picture depth). Check you reference picture often to see where the shadows are, and try to get yours to look similar.
You're not finished yet, there is still the neck and the hair to do. (and ears if they can be seen). Ears are more curves, they are about as long as the distance from the eyebrow to the mouth, and usually don't stick out as far as people think, don't worry too much about the details just yet, it takes a lot of practice to get them right.
The neck starts below the ears and comes down more or less straight then curves out to form the shoulders. You will have to do some shading on the neck and ears to make them match the rest of your drawing.
You're getting close to the end now, just the hair to do, my best advise is to not try to draw every stand of hair, but rather to use the side of your pencil lead and sweep in darker and lighter areas to suggest hair. Keep working, adding details, like eyelashes and shading and freckles and whatever it is that makes this face different from all the others.
When you are done, don't forget to sign your drawing. I always put the date on mine too so when I look at it later I know when I did the drawing. It's a good idea to also note who your subject is, you never know, you might want to do more drawing of that person some other time.