This 3D animation from The Human Atlas explains Breast Self-Examination techniques.

Breast self-examination, or BSE, should be done at the same time each month, right after your menstrual cycle has ended. The first step in BSE is visual inspection: stand in front of a mirror with your hands on your hips. Look at your breasts, paying special attention to any skin changes (redness, swelling, puckering) as well as to any nipple changes (indentation, scaling, discharge). Now raise your hands over your head and check again for any change in appearance or contour.

There are three common methods for the next two steps in BSE. They are all effective, but you can try each of them to see which one works best for you. Regardless of the method you choose, the objective of this step is to feel, or palpate, the entire breast area in both the upright and reclining position, and to notice any changes that occur in the breast from month to month. On palpation, the breast should be soft and smooth when you push on it, like an extra-firm bed pillow.

The line method for palpating the breast involves using the soft pad of your three middle fingers to move in a vertical line, starting in the underarm area and moving down below the breast. Move over a little and slowly move back up. Repeat this up and down motion until the entire breast and underarm area has been examined.

The circle method involves moving your three middle fingers in a circular motion, starting at the outer edge of the breast and working your way in slowly, toward the nipple. Be sure to check the underarm area and the upper chest area as well.

The last method involves feeling or palpating the breast in wedges. Use your three middle fingers, and beginning at the outer edge of the breast, move in toward the nipple. Go back to the outer edge and check the next wedge of the breast. Repeat this procedure until the entire breast is palpated. Once again, check the underarm and upper chest areas.

If you notice any changes or discover a lump or knot that feels like a small, hard pebble, you should contact your doctor as soon as possible. Keep in mind that BSE should be used in conjunction with clinical breast examinations by a doctor, and also with mammography, according to your doctor's recommendation.