Now that you are at level 30, your typical playstyle is going to go something like this: Send in pet/Hunter's Mark, Intimidate if it's ready (if you are pure Beast Mastery), open with a Serpent Sting, let a couple Auto Shots flow and toss in an Arcane Shot. Most mobs will be dead by then.
Isn't being a hunter fun?
Let's see what you'll get in your 30s. And while you are in your 30s, don't forget to stop by Hemet Nesingwary Jr. in Stranglethorn Vale. He and his buddies have a questline that culminates in all sorts of delicious huntery rewards. (If you are on a PvP server, do this quest at your own risk.)
Track Demons you will get at 32. Does what it says: tracks demons. It might surprise you who is a demon. Next time you see somebody innocuously walking a round Un'Goro or Winterspring telling you they love the weather, put on Track Demons.
At level 32 you also get Flare. I don't know about you guys, but leveling on a PvP server this last time around has at this point trained me to be rather deathly afraid of that "zheeeew" noise that happens when a rogue or druid nearby stealths. Now what Flare does, is expose all stealthed units within the range of your Flare. So next time you hear that noise and see a shimmer out of the corner of your eye-- pop a Flare where you think it was and demand that they show themselves!
It is also one of your most used moves in battlegrounds when you are on defense. When I am guarding a flag/node/etc. I will keep some sort of trap refreshed (Freezing/Immolation/Snake, depending on my mood and what I am guarding) and pop Flare every time it's up. The best way to beat a rogue is to catch them at a distance before they pounce on you and proceed to stunlock-stunlock-dead you. I mean it too, rogues at a distance are delightfully squishy.
Moving on, at level 34 you will learn Explosive Trap. This is your first real form of AoE (aside from Multi-Shot which I honestly don't think counts too much.) This is useful when you are trying to kill large groups of things with little HP, and useful for raids/instances where they tell you "everybody AoE!" so you don't feel completely useless. It can pull a lot of initial aggro so be prepared to Feign Death in that last situation there, unless you want approximately four thousand and seventy-three Phantom Guests pounding on you (before they all head to the warlock who inevitably dies. Don't tell me this doesn't happen to your raid too! /shakes finger).
And at level 36 you get Viper Sting. I love Viper Sting. This is when to use it: in place of Serpent Sting on mobs who have mana and annoyingly powerful Fireball-of-Doom abilities that remove half of your pet's HP, and in PvP against casters/healers/other hunters. Using it on other hunters always gives me a sort of sick pleasure; please forgive me if you are Horde on Bloodlust (or Alliance on Nightfall) and I have done it to you. I can't help it.
Always remember it's situational though: if you need to eke out more damage then use Serpent Sting. If the raid boss has a mana pool of over 9 million (oh there I go with the horrible internet puns again) then it's not worth it. Usually, anyways. I've seen some weird boss fights where getting the mana down quickly is key.
And finally you hit level 40! Let's see what you learn:
Aspect of the Pack: it's basically the same as Aspect of the Cheetah except it effects your party! Granted, now that everybody should have a mount, it's not particularly special, but it can be nice for, say, running back to your bodies in an instance after a wipe. Be careful when you use it. If anybody in your party is attacked while under the effects of Aspect of the Pack that person will be dazed. Keep an eye out for your party and if you see something heading towards a member of your party switch to another aspect immediately. The same applies for when you are using this to help out the flag runner in Warsong Gulch.
And do not under any circumstances engage in pulls/boss fights/PvP with this Aspect on. The number of hunters I have come across in Arathi Basin who are trying to protect the flag with Aspect of the Cheetah/Pack on is staggering.
You also get Track Giants which, well, tracks giants.
And lastly, you will get Volley, which is your second form of AoE. Useful for all the previous situations that I outlined and for making cool visual effects in the middle of Stormwind. Do remember though that it is a channeled spell and damage done to you while casting can break it.
Depending on your talent spec, this is usually also where you will unlock access to your 30-point talent, unless you are Pike and always stick five points somewhere else first. Beast Mastery gets the famed Big Red Kitty Maneuver, Bestial Wrath, which makes your pet do some serious damage for 18 seconds and also makes him immune to... basically everything. Survival unlocks access to Wyvern Sting which has its fans and... not-so-big-fans; it'll put something to sleep for 12 seconds and then put a DoT on it. Marksmanship gets Trueshot Aura which will buff the physical attack power of you and your party. Spoiler Alert!!: This talent is getting an excruciatingly awesome buff in Wrath of the Lich King. /spoilers
Well, that'll do it for today's edition of SYWtPaH. I may be speeding things up because there aren't too many abilities left for you to learn (though many of the ones that are left, are important). Go ye forth and do huntery things!