Level your blacksmithing, the extra sockets are awesome.
If you're not planning on enchanting your blues with anything major, look for stam enchants that you can whack on there. They're normally inexpensive.
Enchant your gloves with Armsman
Swap the gems in your belt, aim for stamina. You've over defense cap by far so you can stand to lose some.
Ok ill agree with the armsmen however if there haveing that much trouble it means something your not high enough in damage mitigation or your healer just sucks. If your just starting do what everyone does, look at a nearby blacksmith and get some titansteel stuff going or some defensive saronite stuff itll help fo sho.
So the saronite stuff is like early tank crack. Easy to get into and hard to get out of. It is loaded with defense, but little else. At 535 you're uncritable in heroics, but you're avoidance isn't where you want it to be. I'd endorse the crusaders square pauldrons as a good AH upgrade and then I'd just start targeting the easy heroics and get your upgrades:
- H UK for sword
- Grundak for shoulders (or you can just do the first boss in HoL)
- Get valor medal of the first war with badges
- terrace defense boots h dk
- Gossamer trinket from 2nd AN boss
You and your healer are both on the brink of heroic geared. Just a couple of pieces of gear start you on the down hill slope and it gets easier. Now is a good time to pair up with a good cc'r and use that extensively to cut down on incoming damage. At the moment, I prefer rogues because the disarm is useful for whirlwinds, but there are many options.
You might die more right now, but see it as an adventure. You're both learning as long as you're not getting into some big 'whose fault is it' blame game, there's very few wrong answers. One thing to keep in mind, you don't have to finish every instance you start. If the trinket drops off the second boss in h AN and you can't get the third one down after a try or two, move on. That's a lot easier in guild runs than PUG's as all the pugs will expect a full clear, but guildies will generally help you do gear runs.