New players make a lot of mistakes while leveling there first character in Vanilla. I would highly recommend reading through these tips to save yourself a lot of time and gold.
Don’t buy all of your skills. After the first 20 levels your skills will become very expensive if you try to buy them all. I recommend not buying anything you won’t be using for leveling. Doing this will help you save enough gold to get your mount at level 40. I have a list on other frugal ways to save gold for your mount here.
Just because an item has higher armor or higher damage doesn’t mean it’s better. Always look at an the items +stats and the equip bonuses. The item shown below has +15 frost resistance and an equip bonus of 43 frost damage. I could easily find a chest with more armor but the stats and bonuses make it better. Depending on your class you will want different stats so find a good guide.
You Can eat and drink at the same time. A lot of new players don’t realize this and they can waste a lot of time.
Unless your an experienced mage I wouldn’t recommend grinding mobs instead of questing. If you have done all the quests in an area check out some other leveling locations here.
Not starting your professions while leveling. A lot of people think that getting a profession will waste a lot of money. I personally level mining, skinning, or herbalism along the way and sell all the materials I pick up. If you want to learn more about professions check them out here.
Use the AH to sell your green and non-grey items. If an item in your inventory is grey that means it is useless and can be sold to a vendor. If it has a white name it can be used in a recipe, plan, pattern or somewhere else. Most of the green armor, weapons, and items you find will sell for well over vendor price to an enchanter.
Use Your Hearthstone! When you are out questing and you have 5 or 6 quests completed use it. It only takes an hour to refresh so use it! I see people walk for 3 minutes because they don’t want to “waste it”. Most races have long walks near the end of there first zone so get used to using it. Additionally whenever you leave your first zone set your hearthstone to the new inn.
There are many other mistakes new players make but they will elarn from them. One of the best parts of this game is learning from your mistakes and improving. Good luck out there!