There is another thread currently running on this site entitled "First consensual sex age," where people have responded giving the age at which they first had sex. What struck me was that most said it was anywhere from crappy to just OK. Thinking about it, well yeah - no surprise. Just about anything we do the first time isn't that great, even if you become great at it later on. Think about it: riding a bike, swimming, kicking a soccer ball, we were pretty bad at it and it wasn't much fun the first several times. Sex is the same way: you have to learn the skills, what to to and what not, develop proficiency. Waiting and not doing doesn't make it any easier later - just read some of those articles about women (and men) who waited until they were married at 25 to have sex - things don't work out.
I don't have the magic answer, but I'm beginning to think along the lines, "What is the best age to make your first mistakes and learn?" And "by developing proficiency" I don't mean being a sex worker in training, I mean proficiency in knowing yourself, what you want and how to deal with people. That's the message young women especially need to get, you do what you want with whom you want to do it. You can be taken advantage of by another 15 year-old boy (or girl) as easily as a 35 year old man (or woman). Parents can help by allowing semi-supervised sexual activities to take place at their home: at younger ages, be there in another room so that feeling, fondling, petting can take place without full intercourse, and it's easy for either of them to put a stop to anything that's uncomfortable by drawing attention to themselves or just getting up.