Haven't started healing in earnest, but Marco gave me a few pointers which I passed on to Shermon? so I figure it's worth writing down.
Scoundrel healing is dependent on energy, so energy management becomes a big deal.
At level 17, we have three heals:
Activation: 2 sec (reduced from 2.5 via a 2/2 talent)
Healing: 436-520 (this is almost certain gear-dependent on +Cunning)
100% chance of granting Upper Hand
Channeled: 2 sec
Healing: Heals a target for 24 over 3 sec. (No, that's not a typo.)
Activation: 1.5 sec
Healing: 347-419; requires and exploits Upper Hand
So already, we can do some theorycrafting.
UM: 478 avg heal in 2 sec for 25 energy
DS: worthless healing that's energy free
KM: 383 healing in 1.5 sec for 20 energy
Upper Hand is a Scoundrel passive: Defeating an opponent or activating Blaster Whip or Shoot First grants the Upper Hand, increasing all damage dealt by 2% and enabling the use of exploits for 10 seconds. Up to 2 charges of Upper Hand can exist at once.
I don't have Shoot First yet. Blaster Whip is a 4m range ability with a 6sec cooldown, so as Marco also pointed out to me, Scoundrels want to be in melee range, not shooting from cover. Fortunately, Guardian tanks have their Guard thing that only works within 15m, so yay for that.
The other use of Upper Hand is Pugnacity: Exploits Upper Hand to recover 3 energy every 3 seconds for 45 seconds. Requires and consumes Upper Hand. Does not break Stealth. 35sec cooldown.
Back Blast: 9 sec (biggest damage per GCD, must be behind target)
Blaster Whip: 6 sec (generates Upper Hand)
Vital Shot: GCD (a DOT)
So, to me, that says:
1. Close to melee range -- i.e., stick near the tank.
2. Blaster Whip someone to get a charge of Upper Hand.
3. Shoot things until someone needs healing.
4. Use Kolto Medicine to heal.
5. Use Pugnacity early: either use the energy to keep dpsing or to heal.
6. If you're screwed, hit Cool Head, because you'll regen a ton of energy, and with the 2/2 talent, you'll immediately have 18 energy, too.
And with GCD weaving, you have a 1:4 to generate Upper Hand and a 1:6 to contribute damage to the skull'ed target. Which, ha ha, presumes the tank is marking targets.