Barbed Trap & Venomous Claw are flex skills and can be swapped for something like a heal or damage shield. Vigor from Assault skill line is decent, as is Coagulating Blood for self heals.
If you are having issues with Penetration, use a Sharpened staff instead of Precise.
If you need to proc Off-Balance, I recommend replacing the Flame glyph on your staff with Shock, and replacing one of your flex skills with Wall of Elements.
Skill Rotation
Each skill should be queued up during a Heavy Attack. So hold left mouse click (or Right Trigger if controller) and press the button the skill is on during the animation, it will launch the skill after the Heavy Attack has completed. Rinse & repeat for each skill.
Burning Talons is a semi-spammable skill, meaning you can recast it every 2-3 Heavy Attacks. Try not to recast Flames of Oblivion, Venomous Claw, or Burning Talons before their cooldowns are over, or you will negatively effect your DPS. Some of these skills ramp up in damage over time and recasting them will cancel that ramp up damage.
Use your Standard of Might Ultimate whenever it is available.
Keep up DOTs in this order:
Barbed Trap
Flames of Oblivion
Eruption
Venomous Claw
Burning Talons