Failure to follow the instructions for a given method of birth control exactly as directed is a key cause of contraceptive failure. If you're using birth control pills, taking them at exactly the same time every single day greatly reduces any chance of contraceptive failure and unplanned pregnancy. When using condoms as a contraceptive, it's imperative that they're used properly and in good condition. Women who use a diaphragm or cervical cap need to make sure that the cervix is completely covered before having sexual intercourse. IUD users need to check that the device is in place monthly.