Ilvl is king until you’re in all heroic/m+15 gear or above.
Once you gain the ability to start going to specific secondary stats, stack haste until the class doesn’t feel clunky (IMO this is ~19% before any buffs or into-the-fray benefit) and grab as much verse as you can. Crit is a dps stat only so while learning go haste>vers>mast>crit.
From there, make the reprisal leggo immediately (on feet).
Playing the class effectively revolves around maintaining mitigation (shield block). Generally, while shield block is up, you’re going to be very tanky to physical damage (which is the majority of damage you’re going to take in most situations). Use demo shout and IP regularly, use last stand to recover from a big unexpected hit to buy your healer time to catch you up, and use shield wall to cover the big scary situations. Farm the scale from DoS for an extra oh crap button.
As you learn the dungeons and what hurts warriors and what doesn’t you can start to use shield wall offensively, IE, doing larger multi pulls and using shield wall to survive while your dps blows up the trash instead of saving it for strictly oh crap situations.
While starting out, definitely go into-the-fray and heavy repercussions. This will give you 10% haste which will significantly increase your shield block uptime. Once you get enough gear and/or more familiar with the class, you can opt for ravager and anger management if you choose to do so. (Personally I think ravager is a garbage trap talent) but that’s just my take. More haste means more attacks, more dps, and most importantly, more survivability. Dropping ITF for ravager (which is on the gcd) makes the class feel awful.
Early on ravager was nice for gaining and maintaining threat. With threat no longer being an issue, it’s only worth it to take if you have enough haste without ITF and you enjoy playing without the extra haste.
Other then the above, practice. Use spell reflect liberally since the CD is so short. Definitely go download targeted spells so you can see which person the mob is targeting with their casts, this will increase the effectivity of you spell reflect usage.
Glhf