Hi lycheefan, glad to hear that you are feeling good about starting birth control. We have a really great article that covers both of these questions quite comprehensively for many different kinds of hormonal (and non-hormonal) birth control methods, called
Birth Control Bingo
If the method of birth control you are going to be using is the The Combination Pill (often called "the pill"), then it is covered in this section of the article:
Birth Control Bingo: The Combination Pill, you can also read about some things that do and don't effect its effectiveness here:
Something You Can Worry About Less: Interference and Hormonal Birth Control
If you're using the "Minipill" (the progestin only pill), then check out this section:
Birth Control Bingo: Minipills
Hope you find these useful, if you have any further questions or curiosities after reading, please don't hesitate to ask!