Sue gave you excellent advice regarding breast cancer risks, although I would also add age, alcohol use, excercise and hormones. It would be helpful for you to check out any of the reputable web sites, like the Mayo Clinic, the American Cancer Society, Sloan-Kettering, Johns Hopkins and the National Cancer Institute.
In answer to the second part of your question, I would recommend you talk to your doctor about breast self-exams ( which should be done monthly) and when you should have screening mammograms. You don't give your age, but most of the time the recommended age to start mammograms is 40. Depending on your personal family history and risk factors, it may be recommended earlier but it's up to your physician. Based on comparison of subsequent mammograms to the first one, recommendations for follow up exams will be made. Early detection is the key to survival in breast cancer as in any other disease, so vigilant screening is really important. In the end, we are responsible for our own bodies, so please see your doctor.
The life you save may be your own!
Wishing you all the very best,
The highest risk for breast cancer comes from being female. Family history of breast cancer increases risk. Obesity does too. Smoking does too. Dense breast tissue does too.