I'm a guy but I feel I'm qualified to talk about this because I met my wife online and we had a LDR for over 3 years before we married and moved in together.
The secret to making it work, both in real life and online (but especially online) is to always appreciate what you do have together, not to dwell on feelings of loss over what you're lacking.
Make an effort to communicate every day in a somewhat structured manner and learn to have fun online together. Go through your day and take care of what you need to do, but even with texting set aside some time every day to just hang out together online, sharing links, stories, websites or anything else that you enjoy reading or writing together. Don't get lazy and turn every text conversation into a chore to think of something to talk about, make it happen and take initiative for conversation topics, and really use this as an opportunity to learn how to communicate and share things about yourselves and listen to your partner. Meeting online and chatting for an extended period of time is actually a really great way to open up together and really learn about each other, so make every chat or skype session a chance to really ask questions, have conversations and learn each others feelings on every possible subject matter.
So you can't go hold hands in the park. Don't mope about it, take advantage of the huge amount of fun you can have digitally. There are a wealth of online games that can be played together, from simple browser-based strategy/board games like Die2Nite to games where you can both enjoy virtual worlds like constructing a little life together in Minecraft, or exploring the weird and oddly adult world of SecondLife to geeking out on popular MMOs together. Go to chat rooms together and interact with other people together so your online life doesn't feel so isolated.
Make plans for the future and try to meet up when you can, and during these meetings you should gauge what life together would be like if you're planning on taking it further. Meeting online and having a LDR is one thing, but it's often jarring to be exposed to your SO's real-life quirks and idiosyncrasies.
On that note, BE HONEST WITH EACH OTHER. Just because you can fashion yourself like anything you like and want to be online, does not make it a good idea to be some ideal version of yourself. Be very honest about what you are, who you are and what your habits and life are like or you're going to have a disaster if your relationship progresses. Resist the temptation to invent anything about yourself.
Now this is a huge one that I shouldn't have to say, but from all the stories I read on reddit it bears some repeating: An online relationship is real. Don't cheat. Don't skirt the fine line around cheating, don't listen to friends who will tell you to get a "real" girlfriend or boyfriend, don't dismiss anything about your relationship just because you're separated by distance. If you are committed to someone, even if it's someone far away, you do not have free license to flirt, see people on the side nor are you entitled to getting some physical satisfaction because you feel you deserve to have it. If you can't go without a physical relationship, you have no business being in a LDR.
Seriously, when I met my SO it was in the days of Dial-Up Modems, America Online and there was no such thing as free long-distance, much less smart-phones, skype, messenger and the VAST array of communication tools we have now. We racked up thousands of dollars in phone bills and could only communicate for a few hours a day. But we've been together now for over 18 years and married 15 of those years. I wouldn't change anything about how we met or our relationship.