The best way is to talk to a relative first or your a school teacher and ask them to accompany you, when you are about to tell your parents, in case your parents are very harsh. However, if they are not very strict you can just tell your mother and she will tell your dad.
if you plan on keeping the baby then sit both of your parents down and talk to them like an adult and be very clam about it even if they are mad. try not to let them upset you. if you dont want the baby then tell them your plans and all of you try to work it out like a family.