Its important to first determine the tilt of the head, don`t jump in and draw the features at the start. Choose a subject or photo that is taken at eye level, one that is taken from above or below will introduce perspective problems. Then check how the head is tilted- upwards, downwards, sideways? Sometimes a slight downward tilt with the eyes looking upward can fool you into thinking that the tilt is upward and so on. Front-on views without any tilt are the easiest to draw since both sides of the face are symmetrical – eyebrows, eyes, corners of the mouth and nostrils, ears all fall on the same level. But these can get a bit boring, 3/4th views are the most interesting. Draw a circle and imagine this to be a ball, draw the vertical line from the middle of the forehead through to the nose through to the centre of the mouth and to the bottom of the chin. This line will lie at the exact centre for a front-on view, otherwise it moves to the side. Draw a horizontal line for the eyebrow line. Again this line lies at the centre if the head is looking straight, towards the top for an upward tilt and towards the bottom for a downward tilt. Slice off a section at both sides of the ball to get the side of the head. The ear will lie on the bottom fourth quarter of this circle. Draw the jaw line from the bottom of the chin to the ear. Now its safe to start defining the features..
Learning (i.e. through drawing and practicing) a bit of the bone structure of the skull helps to place the features properly and learning the muscular structure underneath the skin helps us to make the faces express emotions. Its fun to first capture simple emotions like happiness and joy through smiles, grins and laughs then master subtler and more complex emotions. Perservere doggedly through failures, there`s nothing like the sweet taste of accomplishment!