There are tricks of the trade that will keep you alive. The problem is that each of these tricks and bits of knowledge comes at the cost of the lives of your buddies. The ones that worked in I Corps back in '69 won't work in Kandahar 30 years later. Some times they live, most times they don't.
The people on the ground now are at the start of theat learning curve.
One other thing. The trooper who is not frightened the first time they hear that 'WHACK' sound when a bullet goes by is a sociopath.
Agree 110%. Fear is a useful thing actually. Especially if it gets your ass that extra millimeter closer to the ground that's required.