In the mission where you have to fight the infested tanks and chopper. I need some help with that. I have full health, but I always get damaged when I fight the tanks. Then I fight the chopper and I almost get it, but I always die:#. I don't have any resurrection orbs.

Any strategies?

If you take out all the other enemies in the area, you can kill a tank just by standing besides it and attacking it constantly, it won't be able to attack you with any of its weapons. It's a bit long-winded, but pretty safe. As for the chopper, standing at the edge or on one of the pillars and using the missile launcher is quite effective, um... Do you have the missile launcher ? If you don't then the shotgun is the next best option, DT shooting also helps, and try to aim for the eye on its side, weak-spot. Besides that, I can't think of anymore advice, best of luck .