Here in Canada the drinking age is 19 and so, being a university student, I am often tempted by drinking and partying. In fact, it is something I really struggled with before coming to Christ. Here's how I look at it, coming from the perspective of someone who has been there done that for a few years now:
1. There is really no sense in getting drunk. It clouds your judgement for one thing which can be very dangerous. But more importantly, think of how that would look to those you witness to? I recently told all of my non-Christian school friends about how I was saved. If suddenly they see me drinking and partying like I used to, what would that make them think?
2. Some people see no harm in having a drink or two, as long as you still have a clear mind to make decisions and remain a good Christian role model. I agree with that, but be cautious. Some people, including myself, become tempted to have one or two MORE drinks after those first two. I know that having a drink or two with my friends won't get me drunk, but it will sure tempt me to. And sometimes I struggle dealing with those temptations. So why put myself in that situation? Doesn't make sense. Know your limits and stay there.
3. This next one really helped me to change my outlook. Look at what you truly desire in life. Are your actions reflecting that? I used to surround myself with constant partiers and drinkers and I led a similar lifestyle to that. But that really didn't coincide with what I wanted in the future. A godly husband, a family, a strong relationship with God, a rewarding career... I wasn't going to find any of that drinking or going to parties. So instead I've started surrounding myself with Christian people and doing other fun things while my other friends go out to bars on weekends. It's actually a lot more fun and I've learned a lot about myself in the process.
Just some things to consider in the future, hope this helps!
God bless