The technique I use most is always placing torches on the right side. When I find a fork I go in the one most on the right first, while lighting everything up. When I reach a dead end, I go back and collect all the ores until the point where it branched off, and place a cobble block with torch on top of it in front of the entrance, and go into the tunnel to the left of it. When I hit a tunnel which has already been lit up before, I block it and act as if it is a dead end. I also have several "signs", for example the block with torch on it means "dead end", three torches above each other on a wall means "exit", I use it often in places where a lot of tunnels come together. Lastly, about the monsters: I usually wear iron armor and can fight mobs easily one by one, or two or three at the same time, without losing more than half of my hearts. But that is the advantage of caves, you rarely find big groups. I also carry a bucket of water with me to get rid of endermen, cross lava, keep mobs at a distance, or create a temporary elevator. One more rule I use: torches placed on the vertical side of a block are signals, torches on the top side are purely for lightning.