Originally Posted by
Estarliia
If all you're interested in doing is levelling up quickly, I'd suggest using your 2nd talent tree as an Evangelism/Archangel/Atonement Disc spec and run with that, damage is still great and you get free heals (plus faster queues), and I find you pretty much never run out of mana at that point if you just stick to holy fire and smite. Once you're in the 40s you can go back to Shadow and keep mana up with SW: Death from the Masochism talent (glyph of spirit tap is alright but it won't solve all your problems).
Missing so much of Shadow's innate mana regeneration at low levels does suck though, and if you're not patient enough to drink all the time (I know I'm not), then Disc is probably the way to go, for now at least.