I would say either the Cloak, the Belt, t10 gloves with the Frost Badges. Either one of those gives you a nice armor boosts which you are a little low on ATM. But that is just what I would do.
Compare all your items to gear you can buy, write down all the gear differences (like +20str/38stam/-20hit). Then just go down the list of best upgrades.
If you can't figure it out, you should try paladins
Well, before I can give you a full good guide I have to know if you are in a raiding guild, or just pugging your way into ICC. If you are pugging, you won't see heroic-25 for a long time, and that is actually where prot 4-piece shines the most. Also, your chances to get a token is quite low, and you need at least 2-264 to get 4 piece bonus to be worthwhile. So focus on the off-set pieces that do not drop easily.
I recommend to you.
1. Cloak.
2. Belt.
3. Trinket.
4. Go for 4-set, try to not break t9 4set 'till you have 2 pieces of t10. Try to upgrade them to 10.264 asap.
Lil edit: Pimp your shoulder-enchant to the 10k honor one. It's more Stam. Also, put a Heavy Borean kit on your hands instead of that godawful 20hit.
Also, get the crafted feet, it is seriously epic. Put Tuskar's Vitality on it, movement is key for a tank.
And the crafted bracers, seriously those go for around 700 on my server ... and they are really good.
Last edited by Pickwickman; 2010-08-17 at 09:46 PM.