I'm 17 years old and have maintained a steady LDR with a boy since October 2012. I text him constantly. I'll Skype as often as I can. I'm an odd combo of extrovert and introvert, so texting is probably the easiest way to get to it. For me, it is communication. I'll tell my boyfriend that there is a boy somewhere, he knows of my guy friends. He's told me about girls flirting with him, and him turning them down. I'll do late night Skype with him when I'm tired as hell and get derpy, and it gets really funny. I'll watch movies and he'll watch my reactions (I did this with The Pianist... Good god). We care about each other's well being, and like Seba said, sometimes sitting quietly knowing he's there while we do our own things is soothing.
The trick for me is Skype. Catfish will refuse to Skype. I've seen my boyfriend on Skype repeatedly. Someone mentioned cybersex and chatroom nonsense? I told him at the very beginning I will not send him nudes ever. If he asks, I'll dump him faster than he can blink. I recently reminded him of this and he said "After all this time? Good." I won't ask him for nudes either. It's good to leave things up to the imagination and keep thugs a bit interesting.
Now, our biggest problem lies with our parents. My mom watches Catfish and told me once "You better not be doing that" and I'll say "Of course not, Mom... Yeah..." I'm waiting for him to come and physicall be here to introduce him to my parents because having a physical entity would be easier to comprehend for them. Now as for his parents, I posted once (pre-dating) on his Facebook page a birthday joke that said "sexy" (I legit can't remember what it was... But it was one of those stupid jokes) and his parents thought it was vulgar and had him delete it. They later found me as his computer wallpaper when he was at camp and somehow remembered this and flipped shit on him. Not fun. That's a roadblock, along with college, that we have to overcome. But it should get better when he comes in June.