Wowhead and WoWWiki have plenty of information about the ins and outs of WoW (and a database of everything within WoW, in the case of Wowhead) - should give you plenty of info about whatever class you choose to level, and if you run into any problems along the way.
Try to find someone of the same class who knows what they're doing. You can learn tons, but if you're still leveling then just read the abilities. Blizzard is fairly straight-forward when it comes to those.
Ask your friends to help ou questboost you. Also, join some sort of social lvling guild, that did help me alot.
Now i am in a 25 HC 24/7 raiding guild...
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.