The first thing you need to know is that there's no right way or wrong way to check your breasts. You don't need special tools or techniques; it doesn’t need to be done at a specific time of the month, either. You can do it anytime, anywhere you like.
For instance, start with checking them in the bathroom mirror every day... or the shower is a great place, too, where you can use soapy hands to easily feel for changes. Feel all the way up from your breasts to your collarbone, and your armpits as well.
It's as easy as knowing what's normal for you and reporting any unusual changes to a doctor. Your breasts naturally change during your monthly cycle, so check often to make sure you know what changes are normal or unusual for you.
If you've noticed any of these changes to one or both of your breasts, talk to your doctor or a health care provider right away. Thankfully, most people will find these changes to be benign (not cancer), but it's best to know for sure—especially since early detection is so important in the treatment of breast cancer.