Level with a pet if you can because it will help keep you safe. If your pet is tanking all of the damage from the enemies you’re fighting, you won’t have to. The other reason is that pets are easier and cheaper to heal than you are. If you don’t have a pet, make sure you know how to use your defensive abilities. You can’t level quickly if you are dying all the time.
Most of the time you spend leveling will involve questing and slaying monsters, but there’s also a lot of travel. Travel earns you little experience (you do gain a bit for discovering new areas), so it’s wise to keep travel to a minimum. The new level scaling system, which scales zones to your level within a preset range, helps with that. You can choose what zones you want to experience and stick with them until you finish their quests.
You can try joining a Discord server themed around the class you’re playing, how you like to play World of Warcraft (achievement hunting, dungeon-running, player-versus-player combat, etc.), or your location, to name a few examples. World of Warcraft also has player communities built directly into the game. Find a community themed for newbies, or whatever else you want, and you’ll have a great resource to go to with questions. You might even make a few friends (or fellow adventurers).
For your tank... I'm assuming you meant which race should you be, not which class, since you seem to want to be a warrior! Well, if you were Horde side I'd recommend Tauren for the health buff. But honestly, I *never* pick a race based on the racial features - only based on the flavor. If you are going Alliance side, I am quite partial to dwarf warriors myself but pick whatever seems most fun to you!
The Horde levels 50-60 guide has been rewritten and revamped. My 1-60 Horde leveling guide is now completely updated for the 1.12 Drums of War patch. As you can see it is about 15% larger than the 40-50 guide (single largest guide page yet). There is also a lot of route changes. I moved the entire Silithus section from level 55 to level 58, which allowed me to include a lot more quests for that zone. There is also a lot of other improvement to the route, including adding a lot more quests into the guide, mostly from Moonglade, Silithus and Eastern Plaguelands. This will make the final level 59 grind much shorter.
Both guides have a different look. Many players choose the Zygor guide because of the way it looks, with it’s modern, clean appearance. Zygor has improved it, so its easier to navigate. Dugi Guides interface blends into the game more, as it looks more like something you would find within World of Warcraft. It has icons down the right hand side for selecting your guides and is really easy to navigate.
The world quests aren’t necessarily bad, but they aren’t good either. I wouldn’t mind killing five of a type of monster or fighting one particular boss a few times, but after seven or eight, it starts to wear pretty thin. But going from levels in the mid-20s can take nearly 30,000 AP, so you’ll need more than world quests if you want to get your heart up in a reasonable time.
I now have a Patreon Page where you guys can support me while I work on Vanilla WoW leveling guides every day. I appreciate all of you who support me on there, it means a lot to me right now. Doing this full time is taxing on my financial situation. My goal is to make the best Vanilla WoW leveling guides on the web and the donations keep me going at it healthfully. There is also cool rewards you get in return for donating. Thanks!
I do not recommend going for TBC, although I remember Hellfire peninsula to be decent, everything else is rather slow. Instead go for WotLK, Borean Thundra gets you levelled very fast, and then you can head straight for Icecrown at 67, which is also insanely fast, although admittedly has a few elite quests. You can go to Sholazar Basin alternatively. 2 zones should get you 60-80 no problem.