I've noticed a recent trend of Rangers running around quests almost dead with 80% of their mana left and it just makes me wonder "why". You CAN heal yourself, hell you can do it pretty well, and the healer saves mana. Dying and then rebuffing will costs 5 times more mana then you'd use healing yourself. Hell our healing spells are now twice as cheap, I myself rarely run out of mana even while doing all my own heals.
I've seen quests where the ranger will be at 10% health for 30+ seconds while we get to the encounter where he just doesn't heal himself(The healer was empty on mana).
We're a versatile class, don't limit yourself by not healing yourself, because the heal spells that you're neglecting is what gives ranger their survivability.