Long distance can be really hard, but there are some things you can do.
1. Video Chat + other activities. Seeing and hearing your girlfriend while doing everyday activities can be great, and will probably encompass 99% of what you can do long distance.
-Watch a movie/TV show at the same time.
-Browse reddit/imgur/tumblr/etc together.
-Read a book (maybe even the same one) together.
2. Mail her stuff! When you are out and about, look for cute things that remind you of her. Every so often, send her a box of little gifts/snacks/etc. A hand written love letter is highly recommended.
3. Snail Mail. Write each other old fashioned letters back and fourth. Having something physical to remind you of the person can be great.
4. Play online games together. Ideally something you both enjoy. You should take turns choosing the games you play. It can be traditional video games, but there are also on line versions of board games like monopoly, etc. Set up a discord server so you can talk while you play.
5. Send her pictures of interesting things you come across in your day.
6. Order the same meal from a chain restaurant, and eat the same thing at the same time. Add video/audio chat to make it better.
Obviously, you should really aim to meet in person at some point. It might take a lot of sacrifice (maybe saving $100 per paycheck for months until you can buy a ticket), but it is really important. Eventually, if things get serious and you want to really be with this person indefinitely, you should even consider moving to be together.
Good luck!