I agree with Heffner, upgrading the blue slots first will give you the boost from your emblems. Chest, Legs, Shoulders, Ring, Gloves, and then the 75 Emblem helm would be my upgrade path. Personally I was not impressed with the 2 piece paladin tank bonus, at least not while multiboxing, but if it's attractive to you the shoulder and leg order could be swapped to get the 2 piece bonus sooner, however I'm really enjoying the 4 piece bonus.