1. They will play video games; you are way better off embracing it. You will learn key bits of information which will be useful in conversation. Don't know what an MMO or an RPG is? Don't worry they are more than happy to explain this to you.
2. Geeks usually have a specific interest, and the good ones will not shove it down your throat. If they're your friends they're probably telling you to watch/play/read the thing they love because they generally think you will like it. Give it a shot!
3. Fans of the internet will want to show you (videos, articles, funny cat pictures) that they find awesome. Open your mind to Memes, they are hilarious. Geeks also love it when you show them cool stuff. The internet is your friend.
4. Accept that sometimes you will have no idea what they're talking about.
5. Don't insult their interest, unless you want a lengthy and awkward conversation. You can discuss what you like or don't like, just be respectful.
6. Find your inner geek. We all have it in us, just be honest with yourself.
7. Geeks and nerds are not the same thing.
8. Accept that they will do stuff alone, usually at their computer. Use this time to do your own stuff.
9. When you can participate (for example, watching a movie with them), do. It's good bonding time, plus you get a +1 culture bonus.
10. Enjoy your stay in your geekpartment, it's going to be one Hell of a ride!