My answer to this question...
Well, if they are young, group and supervised (family) dates are okay. When talking about "real" dates- when the teenager has learned respect for themselves AND other people. If a female, I would have her take self defense classes before she was allowed to be alone with a boy. If a boy, I would enlighten him as to the psychology of women so he could know when he was being abused/manipulated.
My first true 'dates' where I was treated well led to physical experiences I was way too young for, at 16. From the ages of 14-16, I went on MANY disaster dates (hell, I still do!), so I thought that anyone that treated me WELL was "the one". Looking back, there are hundreds of things I would do differently- but that's a little personal, and I've spent too much time dwelling on the past.
I will say this. I wish my mom and I had a closer relationship, and that I had more self respect when I was young. I want my kids to have confidence. I might be the crazy mom that gives her kids too much freedom...but I will raise them with a sense of integrity and respect.
The strange thing is- both the crappy people and the sneaky gentlemen have shaped me in a positive way (to me, anyway, not to most men). I have extremely high standards and am ultra picky now. I know how I deserve to be treated. If you don't fit, out the door.