Things I do:
run threat consumables, because then my threat is cheaper in mana - more threat per mana. I've been known to flask for 5-mans. I still flask for Kara, which is part of why I can clear it in two hours (the rest is: two SPs, both in my group, no 2nd tank, two healers and T-6 DPS). I always use wizard oil, it's ridiculously cheap.
heavily prioritise a SP in a 5-man.
Wear threat gear. More TPM, more incoming DPS = more mana. If you have to, tank in your healing gear....
If your healer has full mana, and you're empty, back to mob will double incoming damage at least. If I'm multi-tanking, I'll deliberately get stuff behind me sometimes for more mana.
But by far the most important tip is twofold.
Part 1: Read my sig.
Part two: Pull more.
Tune to suit your gear level, but for hero Shattered Halls, I don't have mana problems or have to drink much, but I use
zero CC, and I do things the entire gauntlet in one pull. Gauntlet was the worst for me, constant mana starvation until I worked out the following:
(1) AS on first 3 mobs.
(2) Rocket boots or speed pot
(3) Run to the end of the gauntlet.
(4) Pop auto-blocker or moroes trinket, wings and consecrate.
(5) Hope your healer arrives in time.
Tip: You don't want the mini-boss. Or at least, I don't, but then again, I can't tank Brutallus yet.
Your aim is income damage over 1k DPS, prefer 1500-ish. Tank as many as it takes. Seven mobs pulls in a heroic are about right for that at my gear level.
TL;DR:
PULL MOAR MOBS!_________________
