Grind honor: Do Tolbarad and Wintergrasp, especially the weekly quest. Do the PvP daily on the Isle of Thunder.
Get some ilevel496 pve pieces from Timeless Isle to hold you over until you get proper PvP gear.
Now days there is a catchup conquest point mechanic so even if your late to the game you can catch up really fast by grinding arena games. For example if you haven't gotten conquest points in 3 weeks you will have a cap of 5k or something that you can grind.
As someone said, spell reflect and shield wall no longer require shields. Blade storm actually does decent damage now for arms spec and is viable for RBG and certain arena comps. Shockwave is still good.
You should use slam for your burst rotation. i.e. full rage bar, colossus smash and them slam away your rage.
you also dont have to stay in D stance anymore unless your being trained.. i mostly play bg's and not to much arena.. dont know if the high lvl peeps stance dance or not but in a bg it works out ok for me.. so keep calm and slam on!!!
if you dont have i would get, weak auras addon to track ur CS
Major changes that matter:
Burst is based around pooling rage, hitting colossus smash then as many slams as you can.
You can sit in defensive stance for 25% flat damage reduction, making warriors pretty decent flag carriers. You'll want to swap to defensive whenever you're going to be close to the rage cap and therefore aren't pooling rage. You can also pop CD's and burst someone down while IN defensive stance, provided you've saved enough rage beforehand.
In RBG's, warriors are in high demand because if you take Bloodbath and Bladestorm, you can pop CDs and put a bleed on the entire enemy team, creating tons of pressure on the healers.
Not sure how long it's been for you, but if you haven't been here a while, you can use Intervene to run to a placed banner, meaning you can macro together placing the banner and charging to it for a free extra gapcloser. Also Die By The Sword is a potent anti-melee defensive cooldown, and Shield Wall/Spell Reflect are now usable regardless of weapon (also contributing to the ability to do damage while being trained).
There is also a minor glyph for intervene which makes it automatically target the closest lowest health raid or party member which makes intervene very easy to use if you don't want to bother with mouseover macros etc.