I've been smoke free for about a year. Mind you I was never a huge smoker, but I was in your situation, I started with the kids at school. I think the biggest help for me was just identifying why I was smoking. For me I usually lit up because I was stressed or tired, so I usually smoked after class at school. After that, I found other ways to take care of stress- taking a walk or a run or working out. The biggest thing is just doing something to keep your mind off smoking. That being said, I was still addicted so it didn't always work. If you don't smoke for any particular reason, and you're addicted to the cigarettes, then the hardest but most important thing is keeping your mind of smoking, like I said.
If you tend to light up when your friends do, go somewhere else when they are smoking.
Celebrate your small victories- a day without smoking is decent. Try and keep going. Remember though, don't use the "one more cigarette can't hurt" rule, because the fact is, one more cigarette will hurt if you're trying to quit. Try and go as long as you can- if you have to, try gum or the patch- it doesn't always work for everybody, but it's worth a shot.
Last piece of advice- don't expect it to happen overnight. It might take you really short time, but it could also take you a really really really long time. Good luck!