The scene: Arathi Basin is a 15 versus 15 map where the object is to collect 2000 resources. Whichever side hits this number first is the winner. Resources are collected by holding onto one of five resource nodes: the Farm (which is south of the Horde entrance, the Defiler's Den), the Stables (which are south of the Alliance entrance, Trollbane Hall), the Mines (which are between the stables and the farm to the west), the Lumber Mill (between the stables and the farm to the east) and the Blacksmith (in the center of the map). The map is vaguely circular in shape, with the points arranged around it and one point in the middle.
At the outset of the fight, all five nodes are considered neutral. Players from each side must ride up to the flags and place them in contention for their faction. This is done by clicking on the flag and standing still for a few seconds. Once the flag is in contention, it will remain that way for five minutes. If five minutes pass without any interruption from the opposing team, the node will belong to your side. This does two things:
1) Allows your team to collect resources from that node
2) Allows your team to spawn at that node's graveyard
In order to win the game, your team must have more resources at any given time than the other team. There are a number of ways to do this, but the safest and most effective strategy is to hold 3 nodes and leave the other 2 to your opponent. This is because the more nodes you have, the faster resources accumulate. A team which is able to take all five resources can end the game in literally under five minutes. However, this is very difficult to do with a disorganized group--and let's be real--most of your groups ain't gonna be organized.
Therefore, it is advised to attempt to station five members of you 15 person group at each of the three nodes you wish to take. Opinion differs on which nodes are the most viable--the blacksmith is frequently desired because of its central position, making it easy to launch an attack on any other point with relative quickness. Still, I've been in games where the blacksmith was the ONLY point held by the opposing team. Really, it's all about picking nodes and defending them. For the purposes of specificity, I would recommend that the Alliance attempt to hold, at the outset, The Stables, The Lumber Mill, and the Blacksmith. Substitute the Mines for the Smith if it cannot be taken.
Once you have the points turned to your side, you need only remain at your assigned point for the duration of the game. The only reason to leave a point is if it becomes overrun and is taken by the opposing team OR if another node is under heavy fire and needs reinforcement. Even then, do NOT leave your node undefended. If everyone leaves but you, STAY THERE. Smart teams take advantage of these changes in 'pressure,' so to speak, because logic dictates that not everyone can be everywhere at once. Use this to your advantage when you lose a node. If the majority of the opposing team is beating the shit out of the mine, then they are leaving some other place unprotected. Seek out that place and take it--then you've turned the tables again.
Another key point is that you must call incoming as soon as is feasibly possible. Calling 'INC' when the node has already been turned doesn't really help anybody.
When attempting to place a flag in contention, keep in mind the value of crowd control. If you can sheep, sap, seduce, trap, or otherwise incapacitate a target, DO IT, and DO NOT BREAK IT until you have finished taking the flag. Players WILL interrupt you for as long as is humanly possible, usually long enough for reinforcements to arrive. That being said, when someone is trying to take YOUR flag, do everything in your power to stop them. Do not be afraid to die--the time you purchase with your kamikaze mission can save the node. Always fight on or as near to the flag as possible, and watch for people attempting to take it. You'll know if someone is engaging the flag because red light will swirl around it.
Above all, COMMUNICATE with your team, and make it valuable communication. Don't argue about what to do. Make a judgment and do it. Time is of the essence in Arathi Basin--if someone says COME NOW, it means you should be mounted and on your way. Just be smart about your choices and keep everyone around you informed, and you will succeed.
Finally, don't take a loss too hard. Arathi Basin awards a significant amount of honor even for its losers, especially in a close game. Like all PvP encounters, AB requires quick reaction time and a knowledge of the map, all things that come with experience.