first off if you look at it it will freeze if you stare at it your open to creepers but it will die later if you dont move
now how to kill endermen you will need
1:wepon
1:bucket of water
if a enderman trys to kill you drop water at the area you in and stand in the water
use the wepon if a creeper or other mod try to kill you

why water? water kills endermen if you do 25% damage the mostly will move away form the water and try over and over till they kill you.