How to perform a skin self-examination
Stand in front of a full-length mirror, and use a hand-held mirror along with the full mirror for areas that are hard to see. Examine all areas of your body, including the lower back, buttocks, back of shoulders, and backs of the thighs. 

Any unusual sore, lump, spot, marking, or change in the way an area of the skin looks or feels may be a sign of skin cancer, or a warning that it might develop.

The skin might become scaly or crusty or it may ooze and bleed. It may feel itchy, tender, or painful. It may become red and swollen.

If you notice any spots on the skin that are changing in size, shape, or color, you should speak with your doctor as soon as possible. 

Enlist the help of a friend or family member to examine the areas that are difficult to see yourself, such as earlobes and the back of the head.

Check yourself from head to toe. Don’t forget to check all areas of the skin, including the back, scalp, between the buttocks, and the genital area.

Look at the front and back of your body in the mirror, then raise your arms and look at your left and right sides.

Bend your elbows and look carefully at your fingernails, palms, forearms (including the undersides), and upper arms.

Examine the back, front, and sides of your legs. Also look between your buttocks and around your genital area.
Sit and closely examine your feet, including the toenails, soles and spaces between the toes.

Look at your face, neck, ears, and scalp. You may want to use a comb or a blow dryer to move your hair so that you can better see.