As you level in the World of Warcraft, it might be hard to keep yourself equipped with anything better than stock weapons that come from vendors. While this is perfectly acceptable and sometimes necessary, it’s not always the most efficient way to gain levels because you’re not going to be able to take as much damage, or put out as much damage with these equips.
I strongly recommend staying away from vendor gear as much as possible. Your character will become much stronger if you use gear that adds stat points to yourself. These start at uncommon (green) and they are much better at protecting you as well as getting your damage higher up there.

Where to get these? If you’re a player that is just completely loaded because you have a main account that supplies other accounts or because you buy gold online, feel free to just buy like mad off of the auction house. Buy all of the best equips for each level, if you want to and can afford it.

However, if you’re like the rest of us, you’re not going to be able to afford this as you level. You’re going to have to come up with more efficient alternative methods to getting the equipment you need, and you’re going to have to save your gold for your abilities and upkeep like repairs and food/water.

One of the best ways to get these equips is through the use of forming groups and running through instances. Instances are basically just dungeons that you run through with a party of five, and if the instance is the correct level, it will be somewhat difficult for the players involved, but will drop really great gear for the players that are going through it.

I recommend using addons like Atlas Loot before you start trying to do instances strictly for gear, because through the use of this addon, you can view the drops of the mobs as well as the chance that each mob will drop a particular item. To get atlasloot, run a search on curse.com for it.

Another decent way to get good gear is to either take crafting, or take gathering abilities that will allow you to supply high level crafters with the materials to make you gear. If your character wears leather, take skinning. You can use the skins to give to leatherworkers to make you some really good equips.

I’m not saying to not use the auction house ever. If you can afford it, use it whenever. However, if you can’t, only use it when you really need a certain piece of gear that you can’t find anywhere else. Save your gold. Definitely do not waste gold improving gear that you already have with things like enchants; it won’t be worth the gold you spend until you’re of a much higher level.