I had sex yesterday and i am afraid that i will...

What is the best way to prevent Pregnancy ?
in your case ans you have done sex recently and you don't want to get pregnant so you can use an Emergency contraceptive Pills such as Preven , which should be taken after doctors consultation , and to be effective it must be taken within few hours after sexual activity 
What are the contraception methods ?
Combined OCP such as Diane 
Progestron-only pills such as : Microlut 
IUD 
Condoms 
Emergency Pills 
What are the contraindications of usng OCP ?
Cardiovascular disease 
breast cancer within family 
Allergy 
Strokes 
Arterial diseases 
Liver problems 
Advice :
consult family doctor before using any medication