I use a 4 or 5 D cell maglite. I tried the lantern once but had difficulty using it and the heat/bugs from it were unbearable in our Sept bow season. I might try one again with half shielded and see how that works. I also mark with toilet paper and if there isn't a small bush near the blood spot I push a 12-18 inch stick into the ground and put the TP on top. That way I can look back to find the direction of travel. As someone else mentioned, the when it doubt, back out is good advice that you must sometimes force yourself to follow. If I go 25-30 yards on a questionable hit and the blood hasn't started flowing good I back out. If you can find part or all of the arrow in that first 25-30 yards it can give great clues. I had a buck Monday night that I knew I was a little far back on and was only small dark red blood drops. Found the bottom half of the arrow within 15 yards, dark dried blood and some bright blood right at the break of the arrow but no food/stomach material so I knew it wasn't a gut shot. I figured I at least got liver but still backed out after 25 yards and waited 2.5 hours. Deer was SCD (stone cold dead) at 70 yards when I went back with a hit right through the liver going in and the back of one lung on the far side. Body cavity full of blood with a followable trail of dark red drops and no lung blood until 3 yards before I found him on the other side of a log on the trail.
Doug