There are two major areas that any long range class from rangers, ToS, PoM, Necros, and Demos can easily exploit!
The first and major spot that i find to help raise my KDR is by the second camp -before you enter the main city area - there is a large wall where you get on top of and stop everyone that has to go by in order to get to the main questing area.
In order to do this you climb on the junk by the wooden fence by the camp and face the small wall which when you press sprint and jump at the right moment you can get on top of! and there you are the first spot to help your KDR.
The second spot a little more obvious is past the first set of guards in the noble district, and you go down the bridge and there is a place to climb up on top of there is a great place to stealth and gank who ever come to kill the NPCs there which is really often. there you are two places to help get your KDR up