This might not be useful till Classic comes out, and probably get lost long before then, but I had some random thoughts (mostly about pets) that might help Hunters starting out in Classic in bite sized chunks, so here goes:
Pick out your pet early, before you get to (insert level you can tame said pet at) get the food they like and Pet Skills (if they have any you don't know) before you get your pet.
There are only two stable slots, 5 silver and 5 gold, so you can have a total of three pets.
Pet Skills have levels and just like your skills the lower level they are the less damage they do, keep them up to date if possible. Plan your questing routes so you are not going out of your way to get them, example: running to Silverpine Forest as a Horde to tame a Bloodsnout Worg (16-17) Bite 3 for your Cat instead of waiting till 19-20 and learning it from a Ghostpaw Runner in Ashenvale that's right next to spawns of Clattering Crawler (19-20) who can teach you Claw 3, who also spawns right next to a quest hub and FP for the Horde.
Pets don't auto level, so if you like something that you can only get at low levels, get it then. Pets get Exp only if you do so you can't level you new Strider Clutchmother (20) on level 30 mobs while you are level 60. Also you will be the one tanking if the Pet and Mob levels are far enough apart.
The longer you have a pet the less you have to feed it. Vanilla pets had Loyalty levels (5 or 6 total) once they get to max Loyalty you only have to feed them once in a Blue Moon or after they die.
Feeding your pet will increase its Happiness and Loyalty gain and keep it from running away (or attacking you, hoping they put that in).
Happy pets do more damage, feed your pet.
Feeding your pet gives them a gaining Happiness buff that is removed in combat.
Mend Pet is a channeled spell not a HoT that eats up a LOT of mana, use Bandages whenever possible.
There is a Pet Trainer that will teach you Growl and other Pet Skills, normally they are near your trainer.
You can't feed your pet right after learning to tame at level 10, you get a quest to go into your major city and learn it there.
Bite is a terrabad Focus dump. It has a 10 second CD and only does moderately more damage than Claw (there is no Smack in Vanilla). You can get a pet that only knows Bite but I would not recommend it.
Some pet families have unique skills that do Nature damage, this is the most resisted element in the game (see almost every rock/plant/ect elemental), especially at low levels. That being said, Elemental damage goes through armor (see almost every mob and Player).
Lupos does not do Shadow damage in 1.12, they got rid of that in 1.10 or 1.09 (I think).
Fast Attack Speed on pets is only good for making casters (Players mostly) unhappy, all pets of the same family in 1.12 do the same damage regardless of Attack Speed.
Attack Power (melee) is not the same as Ranged Attack Power in Vanilla (Orc racial, stats on gear, ect) and depending on how they do this AP will not effect RAP unless stated (for Hunters Agility gives us both AP and RAP).
Pets only use the Active Skills (Growl, Claw, ect) on their action bar, there are four slots use them wisely. Drag Growl off your pet bar in dungeons and put Cower on it.
Pet Growl is NOT a Taunt in Vanilla, it increases the Pet's threat.
Aggressive Stance for Pets is a thing in Vanilla, not suggested for any PvE activity.
Learn to macro.
Drag your ammo onto your action bar.
Get a Swing Timer for Auto Shot, learn to move/cast in-between shots.
Log out in an Inn or major city, you get more Rested Exp in a rest area than outside.
Pets don't scale with your character's stats, also they can be buffed separately for your character.
(will add more thoughts as they pop into my head).