Dont be a yo-yo dieter
Every time you gain then lose weight, you get stretch marks around your breasts that are hard to get rid of, says Shirley Archer, a health-and-fitness educator at the Stanford University School of Medicine.


Map out a family-health history
Even if you dont have breast cancer in your immediate family (See: "Do you have breast cancer in your family?"), you may still be at risk if you have first-degree relatives with other hormonally driven cancers, like prostate or ovarian cancer, which are also linked to the BRCA 1 or 2 genes, says Julia Smith, MD, director of the New York University Cancer Institute Breast Cancer Screening and Prevention program.


Move a little more
No time to exercise? Research shows walking just 10 minutes a day starts slashing your breast-cancer risk. A 2005 University of Southern California study found that women who exercised just 1.3 hours a week lowered their chances of developing the disease by 20 percent.


Wear sunscreen

Protect your upper chest from sun damage and signs of aging. Our picks (below): Clarins SPF 30 Sunscreen Cream High Protection for Sun-Sensitive Skin ($28.00; specialty stores) and Origins Sunshine State SPF 20 ($22.50).