the coleman lantern works wonders...i also coonhunt so i have a miners style light that will be in my truck charged and ready to roll if its needed.
biggest thing to keep in mind is TAKE YOUR TIME! a dead deer isnt going anywhere. a deer that is wounded and in a death bed that is jumped out of that death bed is going somewhere and chances of recovering after you jump it as slim because blood is usually done flowing by that time...time is on your side...weather(heat) yotes, wolves etc can make time more tricky....but some knowledge will go a long way.
there a book "finding wounded deer" or something like that by "Trout" ...good read...interesting and gives some good "rules of thumb"
if it aint D E A D in sight, sit tight ATLEAST 30 minutes before climbing down. keep noise and disturbance to a minimum...sneak to the point of impact and look for your arrow, blood etc....replay the shot those 30+ mins...where did that arrow go in? where should it came out? what SHOULD have been cut by your BH?? how long does it take typically for an animal with that wound to die? most deer hit in a killing area(guts, stomach liver etc included) will usually bed within 200yds or less if not spooked...you want to be QUIET when getting down and looking for clues...the longer you can wait the better off you'll be. if you know you center punched the guts or stomach 100% sure and you have the power to stay glued in the tree for 8hrs, your my hero...and if you can do so, you'll likely be rewarded...though i dont think ANYONE can...
learn to watch your arrow flight and shot impacts...under many circumstances, you should KNOW where you hit because you watched it. some people though, cannot watch their own arrow flight...im lucky and rarely miss the flight...last year i WATCHED the broadhead open a hole and watched the fletchings sink into that hole...
learn to watch the deer after the shot....tail up or down? jump? hunch down? run like a bolt of lightning? trot? walk? what was the last landmark it was by before it disappeared? listen! hear it crash?? hear the arrow hitting trees or brush? hear the deer walking/running?? take note of EVERYTHING!
carry gear with you to track deer...toilet paper or flagging tape etc to mark the trail...compass(so YOU dont get lost!) lights etc....i dont carry my miner style light with me but its in the truck ready to go...
friends can help or hurt...you get too many guys that dont know what their doing, they are best left at home. they can ruin the sign you need to be finding. but if you have expirienced friends, they should be the first people you call. save the inexpirienced guys for the BODY search hours after you lost last blood...form a big search party and go through all of the land in the area looking for that deer..
Rob will sticky a post to the top that covers more...im bored and like to type

so i tried my best to answer though theres TONS more that gets discussed annually...being prepared and having knowledge are very important to finding wounded deer