Taking the shot
It is critical for all deer hunters to be able to identify and hit the target's vital areas, generally the heart/lung zone (just behind the shoulder). It is important for all hunters to practice regularly to maintain their skills.
Ensure your rifle is correctly zeroed before hunting, and practise regularly to build up confidence in handling and firing your rifle.
Do not shoot unless it is safe to do so and you are confident of a clean hit. Use binoculars to study the background and the deer's position before firing. Ensure there is a solid backstop, with no other deer behind the target or obstruction in front that could deflect your bullet.
Always try to manoeuvre so that you can rest the rifle for a steady shot; use whatever assistance is available, and watch for barrel obstructions close to you below the line of sight.
Get as close to the deer as possible and take shots at un-alarmed game.
You should be able to accurately judge your distance from the deer and should restrict your shooting to distances where you are confident of a one-shot kill. Be mindful of elevation and windage.
Never attempt head shots. The brain is a small target and one can easily miss, resulting in a non-lethal strike. The animal will run away and you are unlikely to get it even if you follow up immediately.
The final step is to carefully aim and squeeze the trigger. If you are excited, nervous, shaking or puffing and panting, don't shoot until you are calm.
The best shot is the broadside heart/lung area rather low on the chest. There is little meat to damage on the ribcage, and the entry/exit holes will leave an identifiable blood trail to follow.
Neck shots should be avoided unless your marksmanship is such that you can consistently hit the spinal cord within the neck bone under field conditions. If you must take this shot, do so when the animal is facing you. You should also aim low in the neck where the effect of the animal suddenly moving its head is less.