If needed, shoot it again. Do not approach a wounded deer on foot. Lay the deer carcass on its back with legs spread. Locate the sternum or breastbone. Use a sharp knife to make an incision down the belly, from just below its sternum to its genitals. Your incision should be deep enough to cut the hide and the  peritoneum (the thin membrane found just below the skin and over the organs). But be careful to not cut too deep. If you cut too deep you may puncture the organs and taint the meat. After the initial incision near the sternum, make the rest of the cut with the knife blade facing up. This helps prolong the blade's life (as it is not cutting through the fur) and minimizes the chances of you accidentally puncturing an organ. Use a small sharp knife to free the abdominal organs from any membranous adhesions. Once cut free, use your hands to remove the bladder, kidneys, liver, spleen, pancreas, and internal genitalia.  When removing the bladder be careful that you do not spill any contents. To prevent any urine spilling, pinch off the bladder with one hand and slowly cut it free and remove the bladder with the other hand. Take special care to not accidentally cut the intestines or the spleen, as their spilled contents will ruin meat.
Confirm that the deer is dead. Make the first incision on the belly. Remove most of the abdominal organs.