The original Bionic Commando game is kind of tough, especially when you start out. For a while it takes little more than a stiff breeze to kill your hardened combat veteran. Shoot a few enemies, though, and you notice they drop these bullet-shaped things. Collect enough of them and you get these green dots up on the top-left corner of the screen that let you take some more hits.
Now, kind of early in the game you go down this kind of long vertical shaft (*snicker*) with enemies parachuting down all around you. They come down in a pretty predictable pattern of 'just in front of you', and when shot once, they yield the precious, life-giving bullets.
If you work your way down so that you're in one of the little offshoot rooms that has an immovable barrel in it and keep running into said barrel, you'll notice that troops parachute in directly in front of you. Shoot 'em, collect the powerup with the ol' grapple arm, and repeat ad nauseum.
We're running into the barrel, by the way, so that we grapple out to the side to grab the goodie rather than diagonally up to grab the ceiling for no real reason.
Getting two or three lifepoints is probably about all you're going to want to spend time getting, since it takes progressively more bullets to get each additional point. But, hey, go all out and get all 9 if you want to. It'll make the game way easier.