I don't see how people manage to go completely OoM all the time.
Groundrules to keep up Steady:
1. Chug the pot as soon as you can get the full effect of it. Don't use it too soon or you'll waste half of it. Use it too late and you will have less mana to spend the next two minutes.
2. Mana Oils. They are cheap (comparably, a raidwipe due to low dps is more expensive really...) and will have an impact.
3. AotV at 30% mana. It's around there that AotV really packs a manaregen punch. Before that, it doesn't really do all that much.
4. Never let a single second go by without having a pot on Cooldown, unless it would waste it. Keeping yourself topped up makes sure you have that much more to go on until the cd is up again.
5. Get Wisdom over Salvation. Unless you are **** out of luck, Feign will deal with threat.
6. Fuck Stings and Arcane/Multi unless you've got the mana regen of an Innervated Resto Druid. Or Surv Hunter...
This is so freakin' simple! Granted, I'm not in BT/Sunwell at the moment, since I've spent the last six months working on my real life projects, but throughout TK, SSC and ZA at least, I've never run out of mana unless the raid goes retarded on me. There's close calls when you forget to switch to AotV those last few seconds before Pot is back up, but it's hardly enough to make it into a problem.