Get on the roof ( for singleplayer only )
You will survive longer in the game if you get yourself to the nearest rooftop of a tall building.
Find a ladder and climb all the way to the top.
Then go prone and start sniping from the edge of roof.
Be sure however to withdraw from edge and move to another
Location after firing a few shots.
Fire from another position on the roof.
The AI controlled enemy cannot climb up the ladders
To come after you.
I guess they're not smart or brave enough to do so.
However they can still look up and shoot at you so be
Also if they try to throw a grenade at you it will not reach you on the roof.
Added by: Guest Jul 12th 2011, ID#16393