Be patient. Patience is essential to the beta process. Flaws in the software or gameplay are not discovered without time for those problems to manifest. Be a good tester and log on to WoW with the mindset that you might not be in for the smoothest run.
As a beta tester, your patience will be tried. You'll wipe, fail, screw up, die, whatever. It's a game that you're helping to make just that much better. Put aside the gung-ho group attitude and talk to your team about testing -- that helps me focus on the task at hand.