I'd just go into Valkurm, right by the zone point, with your party seek flag up, and sit tight until you get an invitation to join a party. If you're at the zone point, and get aggro, you can just skip across the border. Once you get an invite, you can look at your map to see your party members (You might need to press menu left/right a few times after selecting markers on your map) and walk to them.
As a theif, you'll probably be expected to pull, so be sure to stock up on arrows.