Nothing is going to help you change your habits unless you see a problem/want to change them.

Your friends telling you you drink too much seems strange to me; do you drink with them or mostly on your own? If you're with them and you want to cut back, just ask them to cut you off when you're at their house! If you're out at a club or something, only take enough money for X drinks and don't let them lend you money.

If you drink and smoke mostly when you're at your own house then you have to decide not to buy and/or do other things or be around other people who aren't drinking/smoking.

I did a lot of online school work in my spare time and studying/writing papers/doing school work didn't leave as much time or interest in drinking as I had before that.