Learn your ABCD's. Melanomas are screened by the abcd's: a-asymmetry; b-irregular borders; c-different colors; d-diameber >6mm (size of pencil eraser). If you notice a mole with these characteristics, get it checked out asap. If you have a skin lesion which is growing, ulcerating, bleeding, or otherwise changing, get it seen as well for evaluation and possible biopsy. Best wishes.
"Ugly duckling" sign. In addition to the abcd/e acronym described by dr. Bowman, there is another way to watch for melanomas called the "ugly duckling" sign. The idea is that if a spot looks different than the other spots on your body (i.G., the ugly duckling of the family), it is more likely to be a cancer. The bottom line: "when in doubt, get it checked out.".
ABCD's. Remember your abcd's when thinking of melanoma. Look for moles with asymmetry boarders that are irregular color differences within the same mole diameter greater than 6mm also any new mole or old that starts to itch, bleed or ulcerate should be of concern. Another rule is the ugly duckling rule. Which refers to a mole that looks distantly different from the others on your body.