As a Predator, choose your shoulder cannon then charge a shot by holding the Right Mouse Button. This will consume a small amount of energy, but you can recharge it by pressing T. After that, the game automatically returns to the shoulder cannon. Notice that the shot is still loaded and inflicts serious damage. Go to the Queen at a safe distance with electric view and fire, then simply keep moving in circles while walking backwards and shooting without charging the shoulder cannon. When your energy is out, use the spear weapon to finish it. A couple blows should do the trick. After that, kill the other aliens that appear then move to her head. Use your blades and keep attacking the head. It will increase your trophy number.