As soon as you have collected all of the necessary resources, i.e. mushrooms and the cloth, return to your camp. Follow instructions and craft two poison arrows. From now on, it is a good idea to pick mushrooms from time to time because they are quite an effective weapon. A fired poison arrow has a radius of effect and it is capable of killing a group of as many as several opponents at a time.
In the morning, it turns out that the area around Lara's camp is swarming with enemies. You kill the first one by jumping down onto him off a branch. Press the Y button on the game pad - Lara hits the opponent with her hatchet, but you need to hit him again - press the button again at the right moment. After you kill him, hide in the bushes.