For hormonal or barrier methods to work best, you have to use them exactly the way your doctor or the package instructions say. Even then, accidents can happen. So it is a good idea to keep emergency birth control on hand as backup protection.
The best method of birth control is one that protects you every time you have sex. And with many types of birth control, that depends on how well you use it. To find a method that will work for you every time, some things to think about include:
If you are using a method now that you are not happy with, talk to your doctor about other choices.