use a condom (also use a condom for oral and anal sex)
ask your sex partner(s) if he or she has HIV/AIDS or other STDs , has had sex with someone who has an STD, or has sores, rashes, or discharge in the genital area
get regular check-ups for STDs if you have sex with more than one person. Get a check-up even if you don't have any signs of a STD. A check-up cannot prevent STDs, but it can help to detect them in their early stages so they can be treated.