It appears as though nobody has mentioned one thing that I consider important, which is to make sure you are using your natural point of aim.

Take your rifle, unloaded, and aim at an object then close your eyes for a few seconds and see exactly where it is pointing, it will normally be pointing no telling where at that point. Do this a few times and you may notice that your rifle settles into approximately the same location each time. That should be your natural aiming point, which will be your steadiest position, and you should try to use it if possible.

Richard