You want maximum points in C0unter Strike, Ambush, Death Mark, Death Bl0ss0m. Those skills are on the Cunning Tree. You also want maximum points in Killing Bl0w, Ir0n Hand, Backstab and Execute. Those skills are on the Bloodshed Tree.
My fillings go into Rising Sh0t, Innvervate and Tw0 Fang on Cunning, and I have a couple of points put into Headsh0t on the Sniper Tree.