This is just some helpful advice for anyone just starting out who might not be familiar with the way things work. Sadly in WoW, like the real world, money is a neccesity. Here is what you need money for:
Training: like paying bills, you need to train with new class abilities every two levels (every level once you reach 60). These vary from class to class and level to level as to how much it costs, so don't ask. The higher the level, the more it costs though, so be prepared.
Flights: walking sucks, so being able to fly from SW to Westfall is a luxury you should afford yourself. It also saves time and like they say 'time is money'. (HINT: the tram between SW and IF is free and is actually quicker than the flight).
Professions: If you want to improve your profession skills, you have to pay, just like for class training.
Mounts: At level 30 you can purchase your first land mount. For the skill and mount it costs around 35g. At level 60 you can purchase a fast land mount. This cost around about 640g in total, if memory serves. At 70 you can purchase a flrying mount. The skill and mount cost about 1,000g. (a fast flying mount costs 5,000g for the skill and another 180g for the mount if you go for the bog standard mount). Remember -- walking sucks and at 70, land mounts suck.
Food/Water/Ammo: You should never go adventuring without the essentials.
Repairs: As you adventure, you will suffer durability damage to your kit. Try to repair whenever possible. Once an item gets below a certain durabilty, you start to lose some of the stat bonuses and the items are therefore less effective.
So, where does all the money come from? The main ways to earn cash are questing, looting, and selling.
Completing a quest will usually have some sort of monetary reward. You may also be offered an item or items. If you have a choice and nothing on offer is of use to you personally, then choose the item that has the highest 'sell to vendor value'. All quest rewards are soulbound, so your only option is to sell them to a vendor.
Always loot corpses and always take everything. Bag space may be an issue, so if you cannot loot everything, make sure you dump low value items to pick up higher value items. A lot of people leave grey trash on bodies, but it will sell to a vendor and it all adds up in the end. Always sell grey trash to vendors, never in the AH.
Items of value (white, green, blue, etc.) should be sold in the AH if possible. Not all white items sell well, but some do. Here are the white items I have found sell well in my experience: cooking ingredients, under level 25 shoulders and helms (green ones are hard to come by through questing), engineering supplies, health/mana potions, and any commodity item. For those that don't know, commodities are things like leather, cloth, ore, gems, and other raw materials. Ore generally sells better than bars, so only smelt it if you need to up your skill.
Before delving into the world of the AH, I highly recommend Auctioneer as an addon. It helps to take a lot of the guess work out of selling and buying things in the AH. Also, remember, if you have sold an item in the AH for more than you would have sold it to the vendor, you have made a profit. Some people make money off of buying low priced items and reselling them at higher prices. You need to be very familiar with the realm economy to be successful at this, so only try it if you feel comfortable in your ability to do so.
Besides selling things you get off of corpses, you can also sell the things related to your professions. You can pick up your two primary professions at level 5 -- DO IT! If you are more interested in earning cash and leveling fast, I strongly suggest you choose two gathering professions (herbalism, mining, skinning) as your primaries (HINT: mining and herbalism show up as dots on your minimap, but you can only track one thing at a time, so I don't recommend you choose those two in combination). Crafting takes time and costs money. Gathering costs virtually nothing and you can do it while you are questing. Crafting professions can always be picked up at later levels and generally leveled very quickly and cheaply. Most of the really good items you will want to craft for yourself are for level 70s anyway.
You have three secondary professions to develop -- cooking, fishing, first aid. The only one that every single one of your characters should take is first aid. Being able to bandage is an essential skill. Cooking and fishing only need to be learned by one of your characters (probably your main). There is no cooked item that is soulbound, so food can be made by one and shared with others. High end buff foods sell well in the AH as well.
If you do choose a crafting profession, unless you need to make something for your personal use, craft the least material intensive items that will get you a skill point. Also, try to craft green items rather than white items if you can, as they sell better in the AH. There are numerous free crafting guides online, so have a browse for advice on the fastest and least expensive way to level your craft. You may find that you have to purchase some of your crafting materials. If you do, be patient. If the only available items in the AH are overpriced...wait.
Now that you have earned all this money, what do you do with it. Well, other than spending on or saving for the things mentioned above -- nothing. You do not need to buy gear, because everything you will need to level will drop or be offered as a reward and you do not need to buy enchants. Yes, the warrior standing next to you may have two more green items or a blue item that glows red, but to be honest, he isn't going to level significantly faster than you, so don't waste your money. When you are leveling, gear will only last you about 5 levels before it is replaced by something better. Gear and enchants only matter at the end game and for twinking, not for leveling.
For classes that transition to a higher armour class at 40 (warriors and paladins go from mail to plate and hunters and shamans go from leather to mail): At about level 35-36, start looking at your quest rewards and consider choosing something to put on at 40. Also, start keeping drops that may be of some use to you (even if they are grey or white). Keep these in your bank and by the time you reach 40, you should be able to kit out completely in the next level of armour. True, it won't be the best available to you, but it is free and it is better than nothing. New and better kit will come along quickly once you start questing past 40. The only exception to this is for hunters. There is very little in the way of mail armour that is truly good for hunters below level 60. You might find that leather armour is still better in terms of stats and bonuses (the armour value for leather is lower than mail, but you are a hunter and shouldn't be in combat tbh), so only keep mail armour that will be of benefit to you.
Some general advice:Are you the sort of person who will go into the AH and forget that you need to purchase a mount in five levels and blow all your money? Do you run mulitiple characters with different gathering/crafting skills? Do you have issues with space for keeping things in your bank? Start a bank character. Be aware though, hackers target accounts with bank characters, so don't be obvious about it. Do not name your bank something with the word 'bank' in it. Do not send a level 1 character off to SW to hang out at the mailbox, do the starting quests and put a few levels on it. Do not strip it down to it's underwear -- just wear a basic set of clothes.
Once you have established a bank character, then start funneling all the items you want to sell and the majority of your gold through them. It saves you time as you only have to check mail with one character then on a regular basis and you can concentrate on questing. Also, if your bags are full while out and about, you don't have to go to town, you can just get to a mail box and send the keepers to your bank and dump the trash at a vendor. The big advantage is that if you only run with a small amount of gold on you for daily essentials, then you can't spend your money in the AH on items you probably don't need. If you have to log another character to do it, it gives you time to think 'do I really need this?'.
If you have any questions
, please feel free to ask.
Subject: Earning (and keeping) Gold 
Tue Aug 19, 2008 11:22 am