That was before 4.0.6....
Back to the OP,
This is what I do,
First 90% (100% - 90%)
Cooldown Macro > Steady x2 > Aimed Shot > Aimed Shot > Steady x4-5 (until full focus) > Aimed Shot > Aimed Shot (Until Rapid Fire wears)
Readiness > Cooldown Macro > Repeat above rotation ^^
After that,
Apply Serpent Sting only once then, Chimera Shot > Steady x2 > Aimed Shot > Steady x2-3 (Depending on Haste proc) > Chimera repeat.
For my T12 4pc procs, I tend to use it on an Aimed Shot, followed by a Kill Command, OR Chimera shot to maximize the effect of the buggy-ness we have now.
If you others haven't noticed, your T12 4pc proc only disappears when your 'free shots' hit the target.
On a fight with long bullet/arrow travel time, I can cast Aimed Shot > Aimed Shot + Chimera/Kill Command.