Abstinence from sex and drugs is the only sure way, but eventually most of us end up having sex with someone at sometime. its good to have a back up plan, just in case. if you have sex where a penis goes into an anus, vagina, or mouth, use a latex condom on that penis. if you or your partner is allergic to latex, they have other condoms made of different types of rubber or plastic. they also have condoms that are designed to be inserted into the vagina. whatever condom you use, using water based lubricant makes them work better. if you are putting that penis/condom into a mouth, there are flavored lubricants. if you are having sex by placing your mouth on someones anus or vaginal area, use a sheet of latex. you can buy them or make one by cutting open a condom. dont use condoms made from animal skin or membrane. they dont protect against hiv/aids and other stds!