Summarize the following:
Lay out your thoughts as plainly as possible. Avoid euphemisms, and try to work past your initial discomfort. If you aren't comfortable referring to "sex," try using a similar but "softer" phrase. Instead of saying that you are "having sex," say that you are "making love," or "being intimate," or "getting down." Each of these phrases has its own set of connotations. Remember that sex is perfectly natural. One might argue that, indeed, nothing is more natural. It is how you came into being. If you aren't comfortable doing something, then don't do it. If you let something slide even once, then it will be harder to stop it from happening in the future. Be firm about your expectations, and don't let anyone take advantage of you.  Remember: Consent is crucial when it comes to sex. If you or your partner say no, their answer must be fully understood Before you become intimate with a person, initiate a casual conversation about their sexual health and their testing history. Don't make a big deal about it—just ask if they've been tested recently. Remember that you have the right to look after your own sexual health. You deserve to know if you're about to have sex with someone who might be carrying an infection.  Use protection. It never hurts to use a condom, even if a partner has assured you that he or she is STI-free. If you have an STI, be upfront about it. It can plague your partner for years, and it can have serious health implications.

Summary:
Be frank. Set a clear precedent. Ask about STI (sexually-transmitted infection) testing.