Hi, Maddiaddi. I've always said that sometimes we're the only Bible that people will see. You may be witnessing a lot more than you think you are already, honey, just by the way you're living your life, the way you talk to people, by the kindness you show people. You never know who's watching you and you may be planting a seed and not even know it. Sometimes there are circumstances in life where we may not always get a chance to talk to everyone we want to, so they need to see it in our actions. We're their "Bible." Then other times, Praise the Lord, we actually get the chance to sit down and talk with someone. But a lot of times you have to be careful with some people. Some will run as fast as they can when you bring up God, so those types you need to wait to come to you. Others may see that you're different from other people and may come up to you and ask you about why you're different and then the door opens. So don't get discouraged, sweetheart. I dare say you're witnessing a whole lot more than you think you are. And just say what you can, when you can. May God Bless You!
If it comes up, preach to them kindly and gently. Try not to seem pushy. If they are going through hard times, let them know that you will pray for them; this will usually spring up a conversation. If it is urgent, bow your head and pray for them right on the spot. Or pray for those who are struggling with bad decisions. And you are not alone. Get together with the other Christians in your school. Hope you succeed!
The best witness you could give would be to live your life happily, with honesty and wisdom. If anyone asks you about it, you could give them the reason. I do not recommend going around and preaching to all the kids. There is a time and place.
"Witnessing" has far more to do with being what you are then merely talking to people about Christ. What u are is a "light" as Christ is in u and is the "light of the world". Sharing your faith is a natural "mission" as a Christian. The scripture tells us that Love is the greatest and supreme witness to the reality of Christ and I believe it was the early church father Tertullian that said "they shall know us by our love". The Gospel message u bear is only valid by the Love of God. The Holy Spirit is given for the power u need to be a witness (Acts1:8) ;)
The best way is to live it in front of them. To conduct yourself in a Godly manner! And then they will know you are a christian and when things get rough in their life and they get all down and out, you will be the one they come to for help. You can use that time to witness and show them of God great love, grace and mercy!