When things go bad and get rough....I throw all my good def arts up, taunt the heck outta all mobs and tell everyone else to RUN. I find that I'm usually the leader of the group as well. I tend to group with my wife who plays an Inquisitor, so we are usually just looking for DPS. I always die first. It's our job as a guardian. Good thing is...she usually doesn't let mw die unless we end up in a no win situation. I don't really worry about the deaths...it's part of being a MT sometimes. As others have already noted..it's better to suffer debt for one death, than an entire party wipe. Pick-up groups are usually 50/50, with half being good and the other half horribly bad. When you get into a good group experience, make sure to add those people to your friends list. If it was good to you...it was good to them and then you can start having some good groups more often. Also, since my wife and I duo a lot, we always give aid to others that request help via shout or ooc. You can meet some good players that way and add more to your friends list. If you can find a healer to team up with on a regular basis...even better. A good Tank/Healer combo....one that plays together often and knows each other tactics can make up for some weak grouping experiences.
Just my 2 coppers
Bustayochopps 20 Guardian Befallen
Maelru 26 Necromancer Befallen
Olikath 23 Bruiser Befallen