First of all, you can choose to go through the Dark Portal and fight demons from Outland to upgrade. But when you start your adventure in the first area of Hellfire Peninsula, you will find that the questing in the TBC classic is much more difficult than you think.
Instead of this, it is better to explore challenging dungeons. The dungeon is currently very popular and is one of the best places to farming TBC Classic Gold, so you don't need to spend too much time looking for a team.
You just repeat the Hellfire Bulwark several times with other members of the squad, and you can quickly rise from level one to level two within a few hours. If you want to kill monsters faster and get XP, you can Buy TBC Classic Gold. Players don't have to be entangled in the same place all the time. When a character reaches a certain level, progress can only be made by changing the area.