This is a chicken and egg statement. I tend to be helpful, healing everyone and CCing to help on my tos, or protecting the healer/mages on the team on my ranger or sin. However, once I see they don't care and leave you to die, I tend to become selfish. So I give the benefit of the doubt.
You also have to know when you and your team mates have a chance, and when its just banging your head against the wall. Sometimes, fleeing is the best...