I don't know if these are the kinds of questions you answer, but I might as well ask. I have just started high school, and already I am seeing and hearing about a lot of bad things going on (smoking, drugs, drinking, sex, cursing, etc.). I try as hard as I can to stay away from that stuff, but one of my friends has strayed and is starting to become more like all of those other kids. I know he is a Christian, but what can I do to help him follow the right path? Whenever I try to talk to him about things like this, he just ignores me.
It is a great question. I'm glad that you care for your friend.
The first thing you must understand is that you can't make your friend do what is right. You can encourage him to do right and rebuke him when he does wrong, but the choice will always be his.
One thing I have learned is that people listen more than you think. If you are consistent in your expectations, he will remember. He may not change right away, but he will remember when things go wrong that you were always pointing him in the right direction.
Be careful not to get pulled into his sins. "Brethren, if a man be overtaken in a fault, ye which are spiritual, restore such a one in the spirit of meekness; considering thyself, lest thou also be tempted" (Galatians 6:1). When you care about someone, it is too easy to make excuses for him and to follow what another person is doing.
Remember you're the light for others, so you got to keep you light shining for your friends' sake. "That ye may be blameless and harmless, the sons of God, without rebuke, in the midst of a crooked and perverse nation, among whom ye shine as lights in the world" (Philippians 2:15). Someone has to lead him out when he makes that choice, so be sure you are in the position to do so if you are needed.
Finally, don't ever give up on a person. They may disappoint you many times, but the next time might be the turning point. "Then came Peter to him, and said, Lord, how oft shall my brother sin against me, and I forgive him? till seven times? Jesus saith unto him, I say not unto thee, Until seven times: but, Until seventy times seven" (Matthew 18:21-22).