Line of Force

The best way I can help you see the Line of Force is to get you to take a string, tie a loop on one end and put your string arm through the loop so it wraps around your elbow. Now take the other end of the string in your left hand and hold it out like you are holding a bow. Pull your string elbow back and you will see the string go straight from your bow hand to your elbow. This line from bow hand to elbow is how you can visually see the line of force.

Now that you can see the line of force stand in front of a mirror. Hold your bow hand and string toward the mirror and bring your string arm elbow back around behind you until the string lines up straight from your eye to the mirror. When the string looks straight, your elbow is directly behind the bow hand. That is where you have to get your elbow if you're going to shoot straight. Feel it. Learn to recognize that feeling. This spot can only be found if you're as relaxed as a string under tension.

Practice with the string until you get use to the feeling of how far back your elbow must be to get a straight line pointing right at the target. You may be surprised. Memorize the feeling.
The main reason right handed shooters have a tendency to shoot a little left is their string elbow is not quite back, and because the string shoulder is right of the head they pull their string hand off to the right. This causes the bow hand to counter balance and move left causing a left miss.

Both hands must stay on the line of force without one torquing the other this way or that.