My girlfriend and I have been together for 1 year and 6 months. We've been doing the long distance thing for 9 of those 18 months. It really sucks at first, but the best thing you can do is find a routine that works for you. My gf and I talk on the phone 2x per day at least. Once for sure when she gets off work, and once before we go to bed. We often will talk more than that, but it's part of our routine to talk at least that much. We also don't go more than two weeks without seeing each other. Sometimes we'll go 3 or 4 weeks, but there are also times where I'll see her every day for a month. It'll get tougher as I near Step 1, but it works for us.
You also have to make sure that you're BOTH busy. If one person is an undergrad, goes to class 2 hours/ day and has nothing to do but sit around and pine for the other, then it's going to be really rough on that person when you have to study for 8 hours a day. Also on your off weekends, go out with your friends, hang out, and have a good time.
Also there's the issue of cheating. I know nobody wants to talk about it, but it's real, and it's easy to do if either of you want to. I was actually just talking about this w/ my SO yesterday. Everybody says "oh you just have to trust each other." But we were talking about it, and for both of us, it goes beyond that. It's not just that I trust my gf, I do and I don't want to downplay that, but I feel that I know her so well, that I just know she wouldn't do that. I know she loves me, and I know she's a kind person, and I know her personality so well that I just couldn't see her doing it. And she told me how she feels the same way. It's much more personal than just "trust each other." (also, on a practical note, i personally think it's ridiculous to do so. there is absolutely no point to putting yourself through the stress of a long distance relationship if you're gonna cheat)
Basically, being in a long distance relationship will only work if you want it to. It sounds ridiculous, but it's very easy to either a) get caught up in your own daily routine and "forget" about the other, or b) get so desperate for the other person that you neglect your own life. I know we really hate being away from each other, but we've also grown so much closer, and our relationship has never been better.
ohh... and we live 4 hours away from each other.