Good advice, Bjorn. Very good advice. Let me just toss out some class-picking factoids to go with it:
Beast Mastery-specced Orc Hunters have the highest solo survival ability in the game. Followed by BM Hunters of other races, then Demonology-specced Orc Warlocks, followed by Demo-specced 'locks of other races. Orcs lead this because of their racial that makes their pets stronger.
Druids are the single most versatile class in the game. They can tank (starting at lv 10), melee dps (starting at lv 20), caster dps (from lv 1), and heal (from lv 1). And as has been said before, Restoration-specced Druids are one of the hardest enemies to kill in PvP situations. Their overall survivability is slightly higher than Rogues for the simple reason that rogues can't cast healing spells, and First Aid is annoying to level.
Warriors are insane dps if specced and played right, and are the most common tanking class on most servers. Solo survivability is lower than average tho, since they can't heal themselves without bandages.
Shamans rock, Elemental-specced Shammies are fairly simple to play once you understand the totems, Restoration-specced Shammies are great healers (Chain Heal!) and Enhancement Shammies are absolutely evil in PvP (caster PoV here, I've only really played much as a Mage <_<)
Paladins are NOT easy for beginners to play, but if you want to you can do it. They tank, heal, and have an ok (in general, anyway, some retadins are pretty good) melee dps spec. Holy damage is your friend here.
Which leaves us with Mages and Priests. Priests are hard to get up for the first few levels (low damage) but once you can start speccing Shadow talents leveling gets easier. They can heal or do spell dps. Shadow Priests are absolutely loved by Paladins, since SPriests can regenerate the party's health and mana a little when they do damage and they do even more mana regen for pallies. Priests can get up to 3 buffs that they can give the whole party, and one that they can give one guy at a time. Power Word: Fortitude, which gives extra stamina, which gives extra health. Divine Spirit, which gives extra Spirit which gives extra mana/health regen and gives Holy priests extra healing power, and a Shadow Resistance buff, which pumps up your resistance to Shadow magic. They can also give Fear Ward to one person every once in a while, making them immune to Fear effects.
Mages are flat-out caster dps, no pets to help you, no healing spells. But. For the first 40 levels or so mages have the highest dps available. Even at lv 70 you're high on the damage meters. Frost mages have very very few problems with pvp or solo pve, and starting at lv 30-ish are the best aoe-grinding class available. Pull a ton of mobs, Ice Barrier, Ice Block so they're all close, Frost Nova, Blink, then spam Blizzard. Lotsa dead mobs, one not-so-damaged mage. And you conjure food and water.