Below I am going to show you the easiest way to never (hopefully) see this message again and I'm also going to give you a few tips on improving your toon.
I'm going to write this in point for as I feel it's the easiest way to follow:
- Make a level 1 alt.
- Whisper a Warlock in any city with an Auction House and ask for a summon. Explain to them that this is a bank alt and that you're going to give them 200g when you arrive. When you get there, ungroup and never pay them the money.
- When you are questing on your main, NEVER vendor a White or Green item and ALWAYS pick up grey trash items.
- Send every White / Green item to your bank alt.
- Vendor every grey item.
- Advertise in Trade Chat that you're looking for an enchanter to disenchant items and offer a tip per item disenchanted. I normally tip around 10g.
- Never sell the mats you get from the disenchants, instead stockpile them on your bank alt and use for enchants on your main.
- Find out what items you need for food that will increase your mains atk power / int / spirit / haste / dodge / parry etc etc. Using this food while questing, running dungeons or raiding.
- Save all ingredients that drop. If you don't need them to make food for yourself, sell them on the AH.
- Never sell anything on the AH on the weekend!!! More players online means more items on the AH. More items on the AH means your stuff sells for less!
Hopefully this information helps, please comment if you have any suggestions or queries with any of it!