The following is a method for letting the bow tell where to set brace height:
1. Set a horizontal line on your target using tape.
2. Set the brace height to the lowest value suggested by the manufacturer.
3. Shoot a group with field points at the horizontal line from same distance; 10 to 15 yards. NOTE: Tip of the arrow at full draw is aimed at the horizontal line.
4. Measure and record the group's impact above that horizontal line.
5. Add five twists to the string; shoot another group, and repeat, each time recording both the new brace height and the measurement of the resulting target impact, working towards the brace height upper limit of the manufacturer's recommendation if there is one.
6. Initially the impact point will rise steadily above the horizontal line but then suddenly starts to drop.
7. Go back to the recorded brace height which has the highest impact measurement above the horizontal line and set the brace height to that recorded measurement. That should be where the bow was transferring the greatest amount of energy to the arrow. It should also be the quietest with the least felt hand shock as the by products of wasted energy are usually noise and vibration.