ill give ya a rundown for how i use it on every class:
druid: feral i use to power up garrote, anything else i save for the first time i get kited (cyclone, roots) and use it with ks/shiv
hunter: you can step and get a opener ff before flare outs you, so i use it prefight to cs, then immediately shiv and EA
mage: wait for the blinl, try to save a cp for it too... they blink, your nova'd... step->ks = didnt hafta COS to break the nova, frees it up for w/e you like (neat trick huh)
paladin: power up garrote, you can garrote before cons breaks you if your good with it or the din isnt moving... otherwise just step-cs
priest: wait for the first fear, or the first pissoff timed blackout proc (blackout when they are on the run yields a mindflay if they are shadow)
rogue: when opponent is <15% hp, i use it... it takes them at least 1-3 seconds to realise what happened, it gives you a NICE chuck of burst for the ender and you can usually step-ghostly-ks before they turn around
shaman: non-healing ones i up garrote, healing ones i save it a lil bit.. since you can avoid the totems-sap-kill 2 totems-restealth unless they trinket out.... and i wait for when they kite a lil, then step-kick OR i bait a heal out when im expecting it by walkin away a lil bit (as if to restealth) and step-kick
also good if you hafta go away to kill a poison-cleanse totem/searing totem or honestly want to restealth, since its a nice 'back in their face' move, and if they dont make you use it you get a free stealth lol
warlock: wait for first fear/coil, or for step-cs on felhunter locks (no risk there) ...warlocks panic pretty hard when they burn their first escape move and it yields no results, and didnt bait out your COS
if you step the first fear or coil, your easily safe for the next 3 fears (kick/trinket/cos when u see it coming) and by the 4th try you can re-step
warriors: power up the garrote (important!) and use the 2nd time when they are under 10% hp, since itll buy you a good 2-3 seconds of time to handle them similar to my rogue method... then they execute but cheat death immunes it
step-5evis is a nice finisher but i find i dont get it often without trying for it, step-kick is a lifesaver in 2v1 fights, step-blind is a sucker punch in 2v2 arena (you step the healer who is purposely out of range of your blind, blind em! then back to main target.... you didnt even lose your cp on first target [SOON TO CHANGE, new step adds 1cp... might change that tactic based on situation])