See now personally, as the youth coordinator for 73 parishes, working constantly with kids, I have to agree with Cleopas on the importance of discussing this issue. Not because it's seen frequently in the NT, but because it is a huge problem with our young people. Fornication is almost at the point of epidemic status.
At our Metropolis summer camp every year, the kids are taught about confession and are encouraged to go, to the point that it's really what their whole week revolves around. We typically have about a 98% participation rate, which is wonderful. This past summer, when the priests heard the confessions the first week, they were all shocked to the point of tears at the things they were hearing. It was the number one thing discussed by the kids, and some sort of sexually immoral sin was confessed by almost every one of them. Then, every week, on confession night, after all the confessions were heard, Fr. Grigorios, our Metropolis Confessor (Ierokyrix) got up and, through tears, spoke to the kids about how angry the priests were, not at them, but at what the world has done to them, at how they have to fight so hard to survive against these types of sins.
It is a HUGE problem, so this is one place where I agree with Cleopas.
How we deal with it, however, is a different matter entirely.
If I understand the idea of abstinence rings and that kind of stuff correctly (in that you make a promise), I don't really agree with it. I think it only puts more pressure on the kids and then makes them feel guilty when they have broken their promise. Nor do I think scaring them with stories of std's or pregnancy is the way to go (inevitably, the typical teenage mentality of perceived indestructibility wins out). These things could help when paired with the proper approach, but on their own they certainly won't cut it.
It's not enough to tell them, "don't do it because the Bible says not to." these days, the voices of their friends and the rest of society are often louder than the Bible, unless the whole approach is as follows: it's all about RELATIONSHIPS. It's about three relationships in particular, one of which effects the other two. First, and most important is their relationship with God. That has to be strong and secure. That relationship effects the other two- their relationship with themselves (self worth) and their relationship with others.
We have to teach them about God's love for them, that they are perfect creations of God, living icons of Christ, and the temple of the Holy Spirit. We have to teach them about God's mercy and forgiveness, and that when they make a mistake, the place to go to "fix it" is the Church, through confession.
If they understand this, their relationship with themselves, their self respect and self worth will be able to combat the messages that are telling them that they are nothing more than pieces of flesh to be enjoyed by themselves and others. They will respect their bodies and feel that they are worth waiting for.
If they understand God's love and mercy and their place as children of God and as the Holy people of God, their relationship with others will change. They will feel valuable enough to choose better friends, who, though they may not all be Christians, have the same values as they do, and make smart decisions like they will. They won't go "slumming" with the guy or girl who everyone knows is just out for sex. Instead, they will try to reach out and minister to that guy or girl. And then, when faced with the moment of temptation, they will hear God's voice in their hearts, and His voice will be louder than that of the guy or girl telling them how badly they want them.
How do I say this with such confidence? I've seen it with too many of my kids(I consider all the youth of our Metropolis my kids...). I've seen how raising them up, building them up, providing opportunities for them to grow in their relationship with Christ and educating them in their faith in the process changes their lives in just this way. I have so many success stories from our kids, glory to God!