Two words - education and support.
By educating a girl about her body in all aspects, not just sex, you take away the mystery and stigma. You teach her that sex is not this big bad mysterious thing she should never have until she's married. Teach her about safe sex practices for herself and for any sexual partners she might have. Teach her about STD's, how they're transmitted and what to do if she catches one, but not in the stupid scare tactics way a lot of people like to do.
Get over the idea of 'promiscuity', too. Because guess what? It's a double standard! If a guy sleeps with a lot of girls he's celebrated, but if a girl sleeps with a lot of guys she's shamed. Stop it. If she has multiple partners as long as everyone is of legal consenting age it is no longer your business, even if you are her parent. Instead encourage her if that is a thing she wants to do, and be there for her. Support her if she wants go to on birth control because she's of legal age and sexually active instead of shaming her, or wants to keep some condoms 'just in case' or whatever else.
Remind her of the legal age of consent and that it's there for a reason, but accept once she passes that point she has the legal right. Threatening her or being a controlling parent just leads to secrets, and perhaps even her having sex anyway but in an unsafe manner for a variety of reasons.
So educate your daughter, and then support her. She is far less likely to end up pregnant before she is ready for it, and in the event she does she is also far more likely to come to you for help instead of trying to deal with it herself in a potentially unsafe way.
Having a female child can be a dilemma if not well handled. In Nigeria, parents tend to be very strict and controlling of their female daughters, scolding them when they see them with guys, locking them up so they don't meet up with an boy, forbidding them to mention sex or anything sex related and most girls in Africa see their menstrual periods without ever mentioning it to their parents because of the scary stories they tell us that once you see it and a man touches you then you become pregnant then follows the threats of if you ever get pregnant, I'll disown you, I'll kill you, I'll do this and that. The question is, has this reduced the number of teenage pregnancies and increased the number of good girls in our society? The answer is no, the stricter the parents get the more loose the girls become.
This is because African parents do not understand that it is all about loving your daughter and making her your best friend and not just your daughter. Thing is, they do not follow us to the higher institution and you know how sweet freedom is. Imagine a girl who has gone through all these in her father's house finally in an environment where nobody is threatening fire and brimstone if a man comes near her, surely sure would want to experiment, to explore how much of all she was told is true and then bad friends and peer pressure kicks in setting the ball rolling.
From my experience as a female child and soon to be mother I have learnt that it is all about loving your daughter and making her your best friend.
1. Start with sex education. Tell her about her body while she is growing. Tell her about the parts of her body and their functions. When she reaches puberty tell her why she feels the way she feels when certain part of her body is touched, talk to her about menstrual cycle ovulation, conception and contraceptives. This makes it so easy for her to ask you questions on sex and not hide anything from you. You have become her friend and confidant on sexual matters.
2. While talking to her about sex, be clear on your sexual values. Let her know those things you won't tolerate her doing. Let her know the age accepted by you for her to have a boyfriend. Don't lie yourself thinking forbidding her from having one will stop her from having one. No dearie, it's best you let her know you are okay with it but she has to get to a certain age before having one.
3. Monitor their activities. Get to know their friends and where they hangout. Let her know it is okay to bring even male friends home. Ensure she goes to school when she said she's going to school. Monitor her dressing and how she acts in the public. Does she tend to flirt with guys a lot? Talk to her about it. Know the family of her friends. Make her disassociate herself from any bad influence.
4. Let her understand the importance of education and how getting pregnant as a teenager can ruin her chances of achieving her dreams. Afford her with all necessary tools to have the best education she can ever dream of. Limit her after school activities.
5. Be in control, of what she listens to and watches. Children learn a lot from what they see and hear. Make sure they only listen and watch programs suitable for their age.
6. Lastly, provide them with the basic necessities. Don't give any room for any guy to deceive them with money, love and gifts when you can shower them with all these and teach them to be content with what they have.
7. If you are a Christian, draw them closer to God. It helps build good morals.
I'd suggest sex education from a very young age. I came across a chart this afternoon that kind of explained the stages in a child's growth and what to talk to then about. If I had known this question would come up, I would have saved it.
One can never be sure when it's too early or too late to give the sex education. A lot of things have changed in society and you can't even begin to imagine what these kids go through when you'd think they'll be innocent and safe with their friends. Some people will tell you they had their first experience with sexuality from five and you begin to wonder what has happened to society.
I think awareness needs to be created and the kids need to know what what's good and what what's not. The mothers have a role to play as well as the fathers. The truth is that the girl child tends to be closer to the mother and could confide in the mother more. The mother should do everything to go through child's trust so she could open up to her about things happening in her young life. Any slight shifting from normal should be treated with care.
That's my two cents!