If your deer is shot but not "very fatally," you should wait. A wounded deer will usually lie down within a few hundred yards (often times less). Don't approach it. It will die, and it will bleed out. I like my animals to bleed out well, but I also don't like them to suffer. If you want to finish-off the deer, either cut it's throat (if it is non-ambulatory) or shoot it in the lower part of the neck. If you are bow hunting, don't leave your stand for an hour or so, unless you can see your animal, and can confirm that it's dead. If you get out of your stand too soon, you may spook it. Then, you may have an unplanned opportunity to test your long-range tracking skills. The deer pictured was hit through a ventricle yet it still ran about 200 yds. It was likely dead within ten minutes of being shot, but I waited for about 45 minutes before pursuing it.