Don't gem for hit or expertise. As long as you're uncritable you should gem for straight stam, with def/stam for good yellow socket bonuses and either dodge/stam or agi/stam for red socket bonuses. The T8 chest is a great first choice. For the second choice I'd go with the T8 helm, which although isn't the best for raids, it's probably the best you can get your hands on for a while and the bad raid stat it has is a good stat for you in heroics. A libram(LoO as cmeche linked) is another one you should try to get soon. IIRC this is the best prot libram before T9/Triumph. Your trinket is another weak point. There's a great one in normal cot (the black heart). The one from normal hol is also good, and although the emblem one is good too I wouldn't get it due to having other options and needing to use your emblems elsewhere. From there, I'd concentrate on replacing your blues, then work on all of the conquest emblem stuff and work your way down. Keep in mind that block is ok for heroics and many parts of naxx but is a bad stat in ulduar, in case you're planning to go that far(as in, if you are avoid upgrades with block if you can). Buying things off the AH is another option if you have the gold.