When you are in loose small to mid sized rocky downhills, (like in the first picture) it is helpful to drag the rear brake lightly and accelerate into the brake. This will settle the rear suspension and keep the bike calmer. Pick the common line like on the left hand side of the first picture and cross over to the next best line when needed. If the opportunity presents use a implanted rock or downed tree or whatever to jump over as much loose stuff as is safe. Always look as far ahead as you can, downhills are mind over matter, be aggressive.