A few sudgestions for a stone tank. Personally I have a stone Brute but the theory behind the choices is the same.
1: - Earth's Embrace, Mud Pots and Rooted are your definate friends from the stone primary. As for other armours they depend on your playstyle. You could go for all for variety in missions or go for the pure Granite Build. Even if going for the Granite build you may want to pick the others up on the way so as to be able to take the punishment being dished to you then choose whether or not to respec them out if/when you get Granite.
2: - Swift from the Fitness pool is another friend - when you are rooted and have granite on you move so slow you could swear you are going backwards. Most if not all will recommend you get this and 3 slot it for Running Speed.
3: - Hasten. This cannot be perma anymore but If you are going down the Granite root i'd sudgest getting this and 3 slotting it for Recharge Reduction as when in Granite your powers recharge VERY slowly and this power you will find as a god send.
4: - Again from the Fitness Pool you may want Health and Stamina. The health just to help boost Rooted's regen and stamina because with alot of toggles running you are going to eat endurance for fun.
5: - Make friends with a Kinetic defender/controller. If you go for granite their speed boost will be so welcomed as it will stop you walking backwards, speed up the recharge of your powers and help you with any endurance issues for non stop mayhem. 
I can't really say much about the Fire secondary as I have no experiance with that so i'll just finish by saying have fun and let us know how you go.
Hi there,
.
I'm mainly a CoV guy, but I thought I'd combine subscriptions and try out CoH. After a couple of toons, I've settled on a Tanker and at the moment it's a real blast!
I'm only at 8 atm, but last night I teamed with a D/D Defender and we smashed large spawns easily. Diving in, grabbing agro, it made combat 'tactical' and not just button mashing
I've gone for a Stone/Fire build and I was wondering if there are any powers I should avoid / pick, or any tactics / points to watch out for. I'm hoping its going to stay this much fun and not start to suck in a few lvls.
Anyone with experience want to chip in?
Cheers,
Mike.