A friend and I started playing TERA and have finished the section on Stepstone Isle and are now in Velika. We are in a party together and have added each other to our friends lists. So far any main story quests we've done have been separate, so we were just doing them at the same time.
After some Googling, I found that we can share quests and complete objectives together, but everywhere I look has something different to say on how to do this.
How can we complete quests together? If we can only do certain quests together, how do I tell which those are?