If one of the adds is crowd controllable, you would probably be best off CCing one of them and killing them one at a time.
If not, no fear. Mark one with a skull (healer first), the other with an X, and then the boss with whatever else to denote that you kill him last.
If you can CC one, then let the CC-ing person pull for you - let the targets run towards you into your death and decay (if they need a little coaxing, you have Strangulate for casters and Death Grip for everything else). When you see the trap or CC cast go off, drop DnD between you and the target (obviously not where it will break CC), then if necessary Strangulate the caster and/or Death Grip those stubborn guys that don't want to come punch you in the face.
I like to pop Dancing Rune Weapon in conjunction with Empowered Rune Weapon early in boss fights, personally. The 20% parry early in the fight helps you survive the initial attacks, and of course 50% increased threat output (and damage) is a huge boost as well, helping ensure that your DPS doesn't rip threat off of you while you're building a Vengeance stack.
When dealing with a healer, make sure you have at least 20 RP at all times and keep an eye out for heal casts (this goes for casters in general, but healers are especially a PITA), be ready to spring into action with your Mind Freeze. Remember that PuGs are stupid, never rely on them to interrupt anything.
Other than that it's pretty straightforward. Rotate cooldowns as necessary (Vampiric Blood in particular is something you should use very liberally, it only has a 1 minute cooldown so you can use it multiple times per fight - same with Anti-Magic Shell with casters).
I say rotate cooldowns because it's rarely a good idea to stack them.
As far as self-healing, try to maximize your Death Strike usage if you're not having threat issues (if you are having threat issues, then using your death runes for Heart Strikes would be higher TPS). Rune Tap is on a short cooldown and it automatically refreshes if you drop to low health, so don't be afraid to pop it when you see yourself dipping low and/or the healer is incapacitated/running/afk.