For both men and women, the best strategy is to be thoroughly aware of how your breasts normally look and feel; and then to notice any changes. Your morning shower is a good chance to run your hands over your breasts as you soap up, and also to take a look at them, see if they look the same as they do every day (no swelling, no rash, no nipple changes, etc.)
For women, a yearly mammogram after age 40 is another way to check for breast cancer. And, your doctor should examine your breasts at your annual physical, as well.
Hope this helps - PJH