Level 30 isn't as exciting as it used to be; still, you can pick up Readiness with your talent point, and a second Major glyph slot is available. I'd go with whichever of Mending or Serpent Sting you didn't take at level 15.
Skills, Level 30:
- 30: Feign Death, Mongoose Bite (Rank 2), Multi-Shot (Rank 2), Scare Beast (Rank 2)
In addition to the new skill ranks, your talent point here is probably Readiness. Readiness resets many of your hunter abilities that have cooldowns - shots, traps, Rapid Fire, Feign Death, and so forth. It's useful at the higher ends for resetting Rapid Fire for a little DPS boost, and it's useful all the time for resetting traps and Feign.
Speaking of Feign Death, you pick it up at level 30. Feign Death is what will let you sometimes get away with running through things you can't kill, or survive when the rest of your party wipes. It lets your hunter play dead. (Unfortunately, your pet will not play dead with you, so if you're trying to survive something with an area damage effect of some sort, tell your pet to go play with it while it's not by you, or otherwise send your pet somewhere else. You can always revive your pet, but you have to run back from the graveyard.)
Note that Feigning will shunt the aggro onto the next person on the aggro table, which may be your healer. Sometimes it's better for you to have the aggro if the healer can keep you up long enough to kill it. This is where knowing how to kite is more important than having Feign.
Feigning can also be resisted. Bosses in particular like to resist (or don't care if they think you're dead, they'll still hit you... one or the other). Some bosses won't reset while you're Feigning, so if you're in that situation, just stand up and die, or you'll make your party angry. (Attumen in Karazhan almost always resisted me. My best night: Feigning successfully on every Hydross attempt (about a dozen) for the three hours it took us to kill him the first time. Deaths for the night: 0 is awesome.