Screw packing light, pack what you need. And what you might need. There ain't no Walmart nearby to get your last minute items that you forget.Stay safe bro.
Don't bother with cheap stuff. If you won't trust your life to it, don't get it. You just might have to do exactly that.
What you have has to be functionable. Get what works, not what brand is cool. This is really true of knives.
Redundancy. Have extras. Have a dedicated travel kit. If that means 5 Leathermen so that you always have one exactly where you need one (glove box, bug out bag, belt, first aid kit, etc.) then do it.
There's a lot of lessons out there paid for in blood. Hopefully we'll be smart enough to honor those lessons by not spilling ours.
I think one could get a jump on the book simply by compiling 20 or so of these terrific open-source email letters from soldiers in Afghanistan and Iraq.