Meh, sex is a part of growing up & if they're going to do it anyway it might be best to give advice along those lines. Personally, I'd be happy to give you some ideas provided I'm convinced you're both mature enough to start having sex.

So... tell you what John, why don't you first tell US what you think is important to you both about your first sexual experience and we'll go from there. Hint: start with the basics like: protection.