What Elite skills would expert Rangers recommend for a level 30 Norn Ranger?
I would recommend Rampage as One as your primary elite skill. It syncs very well with Sharpening Stone and Quickening Zephyr for awesome spike damage (when something has to die very fast). The Spirit is good for dungeon healing. The Entangle is only good in PvE and very situational; too many people know how to "break" out of it in WvW to be effective. And Entangle does not seem to work on boss fights in dungeons. Even Champions seem to be immune to it.
What other skills would you consider "must-haves"?
Sharpening Stone and Quickening Zephyr are absolutes for spike damage. These are "required".
Signet of the Wild is good for passive regen.
Signet of Renewal is good for passive condition removal.
Signet of the Hunt is good for traveling (+25% movement). Its VERY nice!
What are your favorite pets?
Snow Leopard and Lynx are good for dps.
Black Bear and Polar Bear are good for tanking and farming solo.
Eagle and Hawk are good for traveling quickly across maps.
Wolf is a good "all-around" pet for unknown situations.
Brown Bear is a good for extra conditional removal and tanking/farming solo.
Carrion Devourer and Jungle Spider are good for dungeons (ranged pets).
What are your recommendations for traits?
PvE - 30/20/20/0/0. I run primary shortbow (secondary longbow) with focus on condition damage and kiting (mobility). Sitting still gets me dead (and I don't like "dead"). So I need skills that I can cast on the move and don't require me to stay in one place. Therefore skills like Healing Spring, traps, and spirits all call for me to be rooted (proximity fixed). So those are no good to me. I would use a tanking bear to hold my enemy in place while I run circles or semicircles around the target. Mobs can case me and cast at me, but my constant movement keeps me nearly invulnerable. My trouble is when I have to change directions or stop moving. The 20 points in Wilderness Survival is only really the lengthen Condition Duration. For this build, mathematically, it does more than the extra points in Precision. Rampager Gear is used with Chrysocola jewels (aimed at getting at least 50% critical chance and then maxing out condition damage). The numbers on the website aren't quite right.
http://gw2skills.net/editor/?fMEQFAVjIVJ2RWaWs2Bg1j96LwmCOlkpwQGLxWaB;T0Ag1yqEUJpSVliKqmMNJay2krJZTjKA In dungeons, you can drop the extra Longbow Range and damage because most fights are in close quarters; I change it to something that will give me more damage.
WvW - 30/30/10/0/0. Same basic idea above, except the Longbow is the primary weapon firing at maximum range (1500). For Longbow, Beserker's gear is probably better with aiming at high power, and critical damage. Ranged pets are good for here, too, as the current AI pathing makes dodging pets at normal speed way too easy. And a pet that does not damage decreases your dps output.
The question you didn't ask:
Buffs (food) - Rare Veggie Pizza (Chef) (extra condition damage)
Buffs - Master Tuning Crystal (Artisan) (extra condition damage)
So that's what I run: Shortbow/Longbow condition damage build with high kiting. I can solo Veterans without my elite skill. I solo Veteran Young Karka easily (though you have to watch you pet closely; sometimes it takes two pets to kill one). I don't know what's available for you at level 30, but I'm sure there's some kind of food and crystal buffs that you can get for a level 30.
At level 80, I'm averaging 101 damage per tick. Add food and crystal and it goes up to 112-117. Add Sharpening Stone and Quickening Zephyr and it can reach 127-133. Add Rampage as One and it can go as high as 154 (though that's the highest I've ever seen it go, so don't expect that "every" time). Its a good "melt your enemy" build. And the best part is that condition damage bypasses toughness (armor). Its a straight attack against an opponent's vitality. Even in WvW, with players carrying condition removal, you reapply it so fast, its almost impossible to keep off. Bleed is on the Shortbow auto-attack skill one. So you basically "auto-attack" enemies to death. The other skills are just "utility" as the situation calls for them.
Hope that helps!