Much has been said about this in other places. Have a reasonable curfew and stick to it yourself. Don’t hang out with friends who sin. You can be friends, but don’t let them drag you into what they are doing. And so on. Like with avoiding tempting thoughts, these actions will help you win the daily spiritual battles.
Since I’ve covered more of this elsewhere, I want to illustrate this with a situation that is less risky than you might experience, but still important. It shows standing up for what’s right can and does help in the long run.
I noted before that I am legally blind. Friend A drove another friend and I home after dinner one evening. He recalls it was before he got saved. So, it was my second, possibly early third year in college, as he was in a different college by then. (I was a year ahead.) This driver had consumed alcohol, and appeared to be safe in the restaurant. But, on the way home, he was louder than usual. Partly for my mom’s sake, if she doesn’t remember, I know I was never in any real danger that time. The worst that might have happened was his driving over the curb before he dropped me off. His words and actions that told me he might be over the limit.
Instead of saying flat out I thought he’d had too much, I wavered a bit. I excused it by saying something about the legal limit being different for people age 18 to 21 and that he might be under the limit if he were 21. (I might have been right. Regardless, it was still against the law. And, more importantly, very dangerous.) But, I still said it was wrong, though I had wavered. (I was a bit of a Pharisee, but like Nicodemus. I always tried to do what was right, and knew there had to be something more to getting to Heaven than just acting good. If this was before I was saved, it was very close to the time I trusted in Christ by faith alone to save me.)
Anyway, later I decided that I didn’t want to ride with him any more; or hang out with him as much if he was going to continue his behavior. He could get vulgar and swear at times, and didn’t always have a great attitude, even if he didn’t drink. If I recall, I discussed how to handle this with a Christian friend.
Friend A told me later that he recalled the incident, and that he never drove drunk after that. He almost never drank afterward, as he was saved soon after that. He said that my testimony had a very positive influence on him. It helped him to stop swearing and such. But, more importantly, I probably influenced not to drink and drive anymore by my refusal to hang out with him as much. I may have saved his life! I could at least have saves someone else, or him, from serious injury. All because I took a stand.