Heads up for the Smugglers (mostly spoiler free):
The Lightspring class quest on Tatooine can be especially difficult depending on how you go about it. The fight involves two Champion level enemies against yourself and a Champion level ally. One of the Champs will go after your ally and will continue to do so as long as you leave them mostly alone. The other spends the first minute or so being CCed, then will act as a healer (who is still quite capable of shooting the crap out of you by the way).
The easiest way to deal with the fight is to bring Corso Riggs, set him to DPS mode and deactivate all his taunts and AoEs (to ensure that the distracted Champ continues to be distracted). When the fight starts, move away and have Corso use his Harpoon on the CCed healer, then spend the next minute or so beating the tar out of it. If you don't manage to kill it before the CC ends, use your interrupt skill on the first heal, then the groin kick during the next heal, and back to the interrupt for the next heal. If you can't kill it in that time, well... you could be in trouble.
After the healer is down, you can simply auto-attack the other Champ to death, if you like. Don't go crazy with the DPS; you don't want to tank it.
And for those wondering about Sawbones Scoundrel healing- the heals at early levels are a frustrating, losing battle against energy loss. But it rather suddenly becomes much, much better at lv30 when you get Emergency Medpac- an instant heal that costs an UH stack but NO ENERGY. With Slow Release Medpac, Blaster Whip, Underworld Medicine and their related talents, you're swimming in UH procs so you get to use this heal a LOT, making it much easier to keep energy regen high. Just be sure NEVER to use an instant cast that costs energy (such as SRM) right after casting UM. Cast the instants BEFORE UM, and only follow UM with EM, Kolto Pack or a second UM.