Is there any basic information I should know?
Sure, YMMV. What you should know depends greatly on your background and goals. What are you interested in? What other games have you played? What do you want to get out of your game time?
Just taking a blind guess, I'd say, try different servers and different mixes of class/race/profession before you settle in. Play on a PVP server differs from that on a PVE server, but things like server population and balance make a difference too.
Expect the game to change a lot by September 25. You're coming in right before a new expansion and will go through the accompanying chaos before you really get your feet under you. Generally, you can expect that your skills and talents will change. There will probably be a rush of activity. Low level materials may be in high demand for awhile around that time because many people will rush to improve crafting skills.
Every crafting profession offers different advantages when you reach certain levels. Some of those advantages are better suited to particular classes. We can give better advice once you know what you're going to be playing, but consider Tailoring. Anyone can take it and I have an old character who is a warrior with Tailor because at that time the bags were useful and it made good money. Today, I wouldn't pick that pairing because after a certain level the special perks of the profession are a better match for someone who will use cloth armor.
A good combo of professions is Enchanting + Other
This is generally true, but I wouldn't suggest it for a new player. At some point, you may want to play around with Enchanting because it can be useful. The easiest combination is probably Enchanting + Tailor because it takes no special gathering skill to feed that set up, everybody gets cloth as they kill certain mobs. As an alternative, Enchanting can be used on a second character so that you can disenchant things another character makes. For example, you might want to experiment with Blacksmithing and discover that you end up with a lot of things that don't sell well on the auction house (AH). Send those things to a second character with Enchanting and you'll find you can disenchant them into things like magical dust and essences that may be easier to sell.
With all of that said, you may want to stick to gathering professions for a first character. Gathering herbs and mining ore will help you get extra experience points (XP). Take Archeology early, the new expansion sounds like there will be more for you to do and it can give you a nice bit of extra XP as you level. Major cities will offer daily quests for Cooking and Fishing, get those skills and try to do the quests regularly. They'll bring you extra XP and a small boost to the skill that adds up over time. That may not seem important, but getting all the secondary skills will help you with a monthly event know as Darkmoon Faire (see below).
Darkmoon Faire (DMF) is a special event that comes once a month. You will be able to do one quest for each profession that is at 75 or better skill and it will bring you XP, money and a boost of +5 skill points for that profession. [Be sure to check your professions before doing the quest! If you are at the cap for a level, you will miss out on points. This can be particularly helpful during certain phases of a crafting profession, where it is difficult to get points.] You will also get a special currency, prize tickets. Prize tickets can be spent for different things, but you may want to start by using them to get so-called heirloom items. Those items are bound to your account, not to the character, and that means you can use them to level more than one toon. Their stats improve as your character gains levels and you'll gain XP faster when using the armor. DMF is the easiest way for you to get heirloom items for a new character, so don't miss the chance. The daily game quests at DMF don't give XP, but they'll help you get prize tickets.
Bags can be a problem for new players. There are two kinds of bags, ordinary ones and special ones for a profession. The special ones usually offer more affordable space, but there are limits on what you can put in them. Bags are sold by vendors and on the AH. At least where I play, vendors are a better deal for regular bags smaller than 16 slot capacity and for special bags of 20 or fewer slots. You'll get some bags as your character goes through starting areas, but you probably want to buy a few as well. So, where do you buy vendor bags? They're in different places. In the Human city of Stormwind, there is a bag vendor in the shop with the Skinning and Leatherworking trainers. Go there for most regular bags. There is another vendor who sells expensive "Carriage" brand bags near the main gate, that's the place to get the 20 slot bag for herbs. Note that each major city also has a vendor, often near the flight point, that will sell you a tabard and a unique bag (meaning only one per character) once you have build up your reputation with that city. The bag is 16 slots and comparatively cheap. DMF also sells a 16 slot bag for one ticket, but it is also unique. You can use more bags than your character can carry by putting extra bags in the bank (usually close to a main city's AH). You start with some space, but will have to buy extra bank slots and there is a limit to how many bank slots you can have (count the bag icons you see when you open the bank by clicking on a teller).
We take it for granted, but you may not be familiar with equipment in WOW. You get it from quests and by defeating monsters (usually a fatal condition for them). Things are color coded: grey is usually sold, replace white gear as soon as you can and start selling it when you find it, green is OK, blue is probably better (but learn to look at stats) and by the time you see other colors you'll know what to look for. Gear gives your character a bonus that helps them be better at their class. For example, Strength is important for Warriors, but Intelligence isn't. As a Warrior gains gear, they will look for stats that give them the greatest advantage. Once you start getting beyond level 20, you should probably start to learn about things like weapon speed and DPS (damage per second), but let's keep it simple. The warrior in our example might be offered two kinds of armor, one with Strength and Stamina and one with Intelligence and Stamina (used by Paladins). The Warrior would be better off with the first, a Paladin might have a slightly harder choice because one play style might prefer Intelligence but another might use Strength. It sounds complicated at first but there are sites like Noxxic
that will help you decide what is most useful for the class and specification you're playing.
There are a lot of other things that might be useful for you, but if I have to keep guessing, I'll end up writing even more of a Wall O'Text and ZAM seems to be disinclined to pay us regular folks by the column inch.
Good luck and have fun! Edit: Yeah, patch day here. Rhode is bored, sober and his usual, verbose self.
Edit 2: Don't get excited, I'm also short on coffee. I meant, of course, maintenance rather than patch. Edited, Aug 13th 2012 10:42pm by Rhodekylle Edited, Aug 13th 2012 10:44pm by Rhodekylle