1.)Open with hidden strike w/ acid blade
2.)Backstab
3.)Shiv
4.)Get stim boost
5.)Apply Corrosive Dart
6.)Shiv
7.)Lacerate
8.)Backstab w/ acid blade
There really isn't a 'rotation' though I'd prioritize backstab first, followed by shiv and laceration.
Your goals are to keep 100% uptime on the following abilites.
1.)Stim boost. ZERO excuse to ever let this drop
2.)Corrosive dart
3.)Acid blade arm pen buff.
Use your rifle shot as a filler for when stuff is on CD. Maintain above 60% energy at all times, but remember you have adrenaline probe so if need be you can burn, pop that and still be okay. Be sure to get the full use out of it every fight.
You can also vanish to open with a hidden strike, but you shouldn't waste it all the time since you may actually need it as a threat drop or to save yourself.