In some parts of the Troll Shaws, where you first encounter the Trolls, try not to approach to kill them because you will not be very accurate, and will die too easily. Instead, stay away as far as possible from the Troll, so that the four Hobbits will hold them off. Afterwards, start shooting the Trolls. Remember that Aragorn automatically aims at distant enemies. Shoot him, and they should die. Note: This can become an issue in some ways. Your job is to protect Frodo, which is more important. If you do not, and the Trolls hit him, he will die and you will have to start the game again at the beginning at Hobbiton.