Understanding the anatomy of whitetail deer, mule deer, elk, moose or other big game is important to making a quick and clean harvest.
Remember to bend at the waist so as to not lengthen your draw and make you miss high. The key is give him a couple hours before you begin to 'track', or in some cases, 'push' your deer.
If I know I have ABSOLUTELY double lunged him, I still wait about two hours before starting the retrieve -even if I see him go down.
Hey, if he's down, he won't go anywhere, but if he's down and re-grouping, pushing him may really make it difficult. You will lose every other deer taking a risky shot like this. A better decision is to wait until the deer turns broadside.
Personally I use a fixed blade broadhead ( thunderhead 100). Sometimes a blood trail can be lost especially if the deer is booking it like crazy through the woods because only droplets can be seen at times depending on your arrow placement. I have found over the years that once a deer is hit and it heads in a direction is will almost always stick to that general direction even if it doubles back it will turn and continue in the direction it started.
Shot a 8pt 205lb deer this morning at 18 yards in the lungs and it only went 100 yards. Particularly in the lungs if there is no pass through think i may have had a lung or airway shot. It will normally stick to deer trails where it can move easily.