In the level BALIN'S TOMB there is a secret that will help you kill the goblins. There is a blue moonlight beam coming from the window and shining on Balin's coffin/casket. You might have heard that goblins weaken in light. Move your player to the coffin/casket, and stand under the moonlight. Goblins will follow you. Once they come close to you, they will also be under the moonlight. They won't attack you. They will just stand there and growl (in other words they are weakened). Kill them, and this way you won't lose any life. I found this out by accident.
However, this technique will not work on the cave troll, coming later in the level.