I think the 2 MOST important things are:
- to NOT take the "all drugs are bad" approach, where you just say drugs are bad/evil/wrong/dangerous etc with no context, no explanation and no differentiation between different drugs
- make him feel like he can tell you anything, don't threaten him or make him feel like if he tried drugs he would have to lie to you about it to avoid getting a lecture or punishment
I think it's really important to be truthful about drugs, tell the kid which ones are really important to stay away from completely and WHY, and which ones might be safe to try when he is older if he chooses. I know that one of the things that led to my drug use at a very young age was the fact that the school programs (and other adults) took the "drugs are bad" approach and so when I tried alcohol and pot with no serious consequences I figured they were probably lying about
all drugs. Drugs in and of themselves are not "bad" or "evil" or "immoral", the problem is that some drugs can be dangerous, have health consequences, and adversely affect a person's life. I also really didn't understand addiction and figured that I could try addictive drugs without getting addicted to them, I would just have enough willpower to only do it once in a while. Kids think they are invincible and that it won't happen to them. Of course the main reason I developed a drug problem was because I was unhappy. So the biggest thing you can do for your brother is do everything you can to make sure he feels loved, happy, safe, and that he can confide in you.
You can discourage drug use without using scare tactics. You can gently explain/show examples of the consequences of drug use and drug addiction. But don't just lump all drugs in together, they all have different levels of risk. I think that education about drugs is power and taking a harm-reduction approach is very important. For example explain what the dangers are from taking too much of a drug and how people die that way, or from mixing drugs, or from using drugs and alcohol at the same time, and explain
why it's harmful to one's life to get addicted to drugs, and that there are certain drugs that are not safe to try because so many people get addicted to them and that a person can't tell in advance whether they will get addicted or do anything to prevent addiction (other than not taking the drug).
But make sure you tell him that if he is ever going to try drugs he can always talk to you about it and you won't get mad at him, he can come to you for advice if his friends are doing a drug and he wants to try it, and you will help him find out whether it's safe to try and how to do it as safely as possible if he insists on trying it. Of course if that does happen and he comes to you and says he's going to try a certain drug, you will actually do everything to try to talk him out of it, but you will be honest with him about the drug so at least he can make an informed decision and do it as safely as possible rather than feeling like he has to lie to you about it.
Kids are going to drink, smoke, and use drugs regardless of whether they have permission from the adults in their lives and if they feel like they can't tell you about it they are just going to lie to you about it. It is really important to raise them in a way that they will be equipped to make good decisions regarding drug use. Saying something like "if I ever find out you tried pot I am going to ground you for a month" is not only going to guarantee that they will lie to you about it, it is going to make them more likely to do it in the first place (it's like saying "don't eat that cake") AND it's going to make them not respect anything you have to say about drugs.
I think it's great to tell your brother that you have chosen not to use drugs and alcohol. Explain why you have made those choices and be a good role model for him. Just make sure that you come across and educated about drugs/alcohol and understanding of the reasons why some people use them, so that he doesn't think you don't know anything about them or that you couldn't possibly understand what it's like to want to try drugs/alcohol or have friends that offer you drugs/alcohol. I think the fact that you don't use drugs/alcohol yourself will be a positive influence on him if you play it right and don't appear judgmental about drug/alcohol use or the people that use them.
Sorry that was so long, I just have a lot of opinions on this subject and wish I'd had someone talk to me about drugs differently when I was your brother's age
