Copypasta'd this from another thread I posted this opener in:

Windbite (Bloodletter) > Venomous Bite (Hawk's Eye + Blunt Arrow*) > Straight Shot (Blood for Blood, Raging Strikes) > Heavy Shot (Internal Release + Barrage) > filler (Flaming Arrow + Repelling Shot**) > filler until DoT reapplication

Filler is basically Heavy Shot and Straighter Shot procs. If you get a Bloodletter reset during the opener, weave it in and pick up from where you left off. Blunt Arrow and Repelling Shot are optional due to animation locks, along with whether or not you are on silencing duties for the former, and whether or not you're in a safe position to use the latter. Most importantly, this rotation allows you to reapply your DoTs with all the buffs up without having to clip them too early. Oh, and if you're using a HQ X-Potion of Dexterity, use it after Internal Release and before Barrage in the opener.

If you have any more questions about this opener, do not hesitate to ask.