Visualise the exit
Pick a point on the far side, just behind the last rib, and draw a line from it through the heart. Where that line exits the near side is your aim point.
When to pass
On large game with light bullets, or with a bow, the shoulder bone can stop penetration. Wait for the animal to turn.
Typical miss
Hitting the near shoulder too high and outside the chest, breaking bone without reaching the vitals.