Try to do dungeons a few times each just for the exp. its better to hit a quest circuit where a few of them are green (where they were yellow a level before) which you can usually do by grinding mobs or grinding dungeons (so you have dedicated heals). Make a friend who is doing the same quest circuits as you who plays a class with healing so you can play a little more aggressively. Warrior can be a bit difficult to 30, but then (if arms) you get Sweeping Strikes (“SS”). And then at 36, you get Whirlwind, which when combined with SS, can hit 2-4 mobs at once for a nice chunk of damage every 30 seconds (SS cooldown). Yes, 3 mobs will be hitting you instead of one, but you’ll also be landing a huge hit to all 3, and then can work them down relatively quick btwn cleave and follow up WW 10 sec later.
As a general rule, don’t overuse Heroic Strike unless you have a ton of rage and no other attacks to use (or cleave, really, unless you have a ton of rage and 2 mobs). Using either prevents your next autoattack (no rage gen), and then uses rage to cast the ability (so a rage loss, minus incoming rage from dmg which is almost never going to fully offset this exchange). Once you get WW, better off just build rage, WW, cast a hamstring, autoattack, WW again when off cd then to try and use Heroic Strike every time you have 12-15 rage depending on talents. (edit: Don’t over use it AFTER 30, because really before 30 you won’t have really anything else worth attacking with for dmg, or using rage on routinely)
Use Berserker Rage when you know you will be getting hit by mobs, so basically every 30 seconds during questing. If you are on a PvP Server, you may want to consider reserving usage in case you get into a skirmish with a warlock/priest/other warrior using intimidating shout.
Also 40 = Mortal Strike (Or blood thirst if Fury, but not as good) so that’s another instant attack that doesn’t prevent your next autoattack.
It picks up in your 30s, but its never a cake walk unless the mobs you are fighting are both non-elite and same level / lower.
OH! and make sure you buy the mats for your level 30 warrior quest (WW Axe/Sword/Hammer whatever, go axe) at 30, and ask a higher level friend to help you complete it by helping you kill trolls in STV (lvl 34-39) and Cyclonian at the end (lvl 40 elite). That axe will last you a looooooong time and its amazing if you went Arms and got the 5% crit talent from axe weaponskills.
good hunting/leveling!