1. If you want one of those big strong pets be a Hunter.
2. Animal loot is worth more than armour or weapons.
3. Enemies drop bags occasionally, the coloured ones are even worth more than the brown ones.
4. Professions come in pairs for a reason! Tho some can have different pairings like mining, it works with blacksmithing, jewelcrafting (available in burning crusade) and engineering.
5. If you choose skinning and leather working the kits you can make to reenforce armour etc can be used on any armour not just leather.
6. 'Critters' can be skinned, fer instance sheep yield wool cloth when skinned (sometimes, may depend on skill level)
7. Be wary of groups asking you to join them, they may have crappo loot settings...
8. Use the underground tram thing between dwarven lands and human, it's free and means you have access to each other's low level quests. It's in each of the two cities.
9. If you find yourself with extra bags keep hold of them, you'll want them later! Whether to put as an extra bit in your bank, or to send to another of your characters.
10. make a few characters. Give them dif classes, professions and specialties. Then you can use the mail system to swap things between the two.
11. Guilds, you can leave by clicking on the party options (top left). You can also leave a group this way.
12. To start a guild you need to have a guild charter (10 silver) and get 10 people to sign it, they can't be in a guild already and if one of the joins another guild before you take you're charter to be ratified then you will have to get a new signature. A Guild bank costs 100 gold. Tabards, which don't seem to have any use, also cost gold.
12. If you stand around in one of the cities you will eventually see people selling gold for actual money. Use your own caution here. I'm a purist so I'm not going down that route.
13. Kill things. Lots of things. When an enemy's level is a grey colour you aren't getting any experience for killing it, but you can still farm items from them.
14. If you are a normal player (not player vs player) you may come across a player from the other faction, you are able to attack them, but they tend to be a tad bastardly, def don't attack if they've got glowy weapons!
15. You can speak to guards and they can give you directions, the correct direction will show up as a golden arow in your mini-map, then as a flag when you are close.
16. you cannot post soulbound items, so if you want to give a good weapon to one of your other characters don't equip it. However most things gained from quests bind to you when you get them.
17. Ignore weapons damage, look at damage per second.
18. you can learn weapon specialisations from certain trainers, all found in the main cities. There aren't many trainers tho.