Are you free from all curable diseases?

There's no way to be sure unless you get tested at a clinic or by your doctor. (I think the clinic is a better choice: they're more familiar with sexually transmitted diseases.)

Sex should be responsible, consensual and equitable. That means you watch out for STDs (and pregnancy!); you only have sex with a willing partner (and no bs-ing to get into the sack!); and you make sure that both of you enjoy the experience.

Play Safe!