On my first playthrough I gun'n'run for the most of it, using stealth on just a few levels. On the second, I'd used alot more stealth/conservative, using throwing knife more in stealth part and punching weak/meduim enemies with the knife. That was realy annoying for me, I tried to stare my way through only finding myself punched in the back while staring the second one. So I just blast/run through with the heavy shotgun
In the beginning I didn't really know any of the stealthy routes, but during the third playthrough, the first time I played any other difficulty than "Easy" (Ranger Easy), I found it almost impossible to win by run 'n' gunning, and you lost a lot of ammo. But I usually alarm someone halfway through, and sprint through the rest of the area from there
I really love going stealth in this game, and spend all my bullets on silenced weapons. In levels like Dry Station and Black Station I spend a lot of time sneaking around deciding who to kill first, and the best way to take everyone out without being spotted. It's fun until I do get spotted and everyone knows where I am from then on. So a lot of the time I start out using stealth, taking time to douse lights, but end up in a huge firefight anyway.
On my fisrt playtrought i used my play style: "If it moves-shot it, if it doest move- move it by myself and then shoot it " And yes on the Library level i somehow skipped the sentence when they say to you just look them into the eyes so i just gunned all of the libraries... well it took me longer then to finish the seecond part of the game and i had only small amout of pistol ammo left after i killed those nerd-monsters :/
I, like most beginners, took a "run-and-gun" strategy in my first playthrough. After discovering how much more beneficial taking a stealth approach was, I've stuck to that.
first playthrough, gun and run, after that a combo of both, but I prefer stealth. I always upgrade to silenced and scoped weapons, except for the volt driver, that I only use in librarians and demons.
Best way to get through the levels : Library and depository is to run through it. Ignore the Librarians. With just your compass, you can run through the entire level.
I played through each level with a Stealthy approach. Using mostly Throwing Knives and a Silenced Revolver. But when things got too crazy I broke out the Heavey Automatic Shotgun and the Kalash with the Laser Sight.
In every game, I prefer a fast, clean and efficient shock-trooper approach. I try to nail isolated enemies through stealth, but when I encounter groups, I go full convent, with a scoped AK-47 and an automatic shotgun w/ bayonet attachment. Nothing is more beautiful than watching a Nazi wriggle on a blade. When they spot me, I try to maneuver around and herd enemies into a cluster. After this happens, I toss in a sticky grenade (a grenade with sharpened nails) into the mix, then it's "Good night, Gracie." These tactics have worked for me no matter what difficulty I've played Metro on. You just have to know when to retreat and you have to remember to scavenge like a mofo.