For gosh sakes...know exactly where the deer was standing when you shot it, where it ran after you shot it, and the absolute last spot you saw it last before it disappeared. Be observant of deer behavior after the shot. Did it do a high mule kick? Did it tuck it's tail and hunker and run? Did it bound away with the tail flying high in the air? Try to find the arrow if you can because it can tell you volumes in regards to where the deer was hit by the color of the hair, the color of the blood, the smell of the arrow or particulate matter on the arrow (hopefully it doesn't smell like arse), and if there are bubbles in the blood hopefully indicating a nice lung shot. Without the arrow it is possible but much more difficult to discern these things. Tracking an arrowed deer is like putting a puzzle together...the more pieces you have that fit the more accurate a picture you can see and a much more effective retrieval strategy you can formulate.