Well figuring that DA:O will be the same as Fallout 3, Mass Effect, or Borderlands seems to be you're first problem (don't know about KoTOR, never played any of them). I've found that in DA:O you have to work as a group not a bunch of individuals. Rogues can't take that much attention and mages die in a stiff breeze. On the other hand warriors can't survive forever without a dedicated mage healing them (unless you want to really entirely upon health potions which I've found is a bad idea). As for the enemy, take out those mages. They'll die in a couple shoots but they can ruin your entire day if you let them. They are glass cannons in the purest sense. Rogues do better when they're backstabing and warriors should be the ones gaining all the aggression (they have several abilities that increase their "threat" to the enemy).
As for your mission, try to take the darkspawn piecemeal. I think I know what area you're talking about and I believe that you're just rushing into the main area and getting your ass handed to you. If you can take out the darkspawn in groups, it becomes alot easier.
Other than that, it comes down to learning all the little details such as which talents you should take and what skills you should sink points into. I know that a badly contructed party can have a devil of a time getting through certain areas.
As for your mission, try to take the darkspawn piecemeal. I think I know what area you're talking about and I believe that you're just rushing into the main area and getting your ass handed to you. If you can take out the darkspawn in groups, it becomes alot easier.
Other than that, it comes down to learning all the little details such as which talents you should take and what skills you should sink points into. I know that a badly contructed party can have a devil of a time getting through certain areas.