Are you playing your warrior manually?
You have to understand the class and all is abilities, I guess that goes for all classes. As pointed out already by others, gear and maxing out your AA's will go a long way. Grind away and complete collection sets to get the AA's. The good news is warriors don't have a ton of AA's to max out. Learn how to rotate your disciplines, figure out which abilities can stack. Warriors have lots of emergency abilities to use when the going gets tough. Fortitude, flash of anger, tenacity, resurgence, to name a few. I've been in a group where the main healer didn't realize he was the main healer, and thought I had a Merc out. He finally spoke up and asked if my Merc was set on passive. I told him we have a full group and no mercs are out. The only heals I was getting from him were nuke heals. A well played warrior can survive through a lot. But in order for any of us to help you out, we need to know exactly what you need help with and what your doing during a fight.