I always dps while questing on my sawbones, while keeping hots up and healing for elites.
as a scoundrel, melee abilities are your best friend, I'll generally engage a group by stealthing, tranq'ing a tough mob if there is one, back blasting my target then a pistol whip and quick shot to finish him off, grenade the next target and run up to him for a sucker punch and quickshot / pistolwhip, or dirty escape with a sucker punch and another back blast.
grenades are great knockdowns for farther away enemies while you engage closer enemies with dirty escape. Don't forget about your flashbangs too. Best way is to try to keep as many enemies locked down as possible, with pugnacity fueling your quick shots, and just cut them down one at a time.