In missions where you have to kill an important figure in a certain way 
(such as pushing them off a
roof or into a furnace), you can do this easier by luring the enemy over to 
the hazard you must use
to kill them before fighting with them. Just avoid them and run over to the 
hazard. They will come
over to you. Beat them up a little, but do not kill them completely. Then, 
grab them by holding L1
+ R1, and swing them so they have their back to the hazard.
Then, push forward with the Analog-sticks to shove them to their death.