5v5 is the hardest arena forum, so when we do pull enough of our team together to play, we don't always bother speccing for PVP. We just go in every week, die enough times to get arena points, and go our separate ways until we can scrounge enough gear to be an actual team.
You can read all the strategy in the world, but the fact is: you can't win if you aren't geared in proper PVP gear. You need resilience. And the best gear comes from the most current arena set, and the arena sets are available to purchase with arena points, and you get the most arena points from doing 5v5.
Facts You Want
Points: Play 10 games minimum a week. Each member must play 30% of games to get points. The more team members are required (2v2, 3v3, 5v5), the more points you get for the same rating. (I get a few hundred points a week from just the 2 teams.)
Do not worry about your rating when you're just starting. You start at 1500. It will go down. That's just the way it is. There is no way around it except to spend 80 gold to start a new team when your gear gets maxed.
When: Arena teams reset every Monday at midnight, so always play before Monday or the wait time for each game will be ~10 minutes. You will see some minor slowing on Sunday nights as well. Nevari and I had ~4 minute waits on Sunday.
Death: If you get really frustrated when you're zerged in battlegrounds (killed by many others with no chance to fight), buy some PVP gear with your battleground honor (AV at 70 gives the best per game, win or lose, at the moment) before you try arenas. My husband is extremely frustrated by overwhelming opponents, people who kill you before you can move, and he won't play arenas until he can properly gear from other sources, because they make him angry.
Teams: You can be on one of each type of team: 2v2, 3v3, 5v5. Each team can have up to double the minimum number of members (so 4, 6, 10). For example, Manasseh, Nevari, Shenoah and I are on the 2v2 Tiger Pants Death Squad, and those are all the players we can have on that team.
Grounds: There are several different arena grounds, and they are physical places in the world. So you can go look at them before you do arenas -- however, landing on the last two in my list will mark you for PVP like the Gurubashi Arena, where anyone (horde or alliance) can attack and kill you: Ruins of Lordaeron, Ring of Trials, Circle of Blood.
First Time: You will be confused, freaked, and miserable. You can do a few trial runs that don't affect your rating, but the wait time for those is pretty long. Don't give up on arenas because of the first couple of games, though. You'll get used to it, get into a dying groove, and learn from what you did wrong so you can remember it for when you get to play with good gear.
Length: Games are usually under 2 minutes. The outcome is swift and decisive and usually in favor of the team that gets the first kill.
Annoyed by Chatting
One thing I really hate about arenas is that same-faction teams can talk. And teams that destroy you like to gloat. Because they're jerks. (The ONLY reason to talk out loud in arenas, unless the rest of your team disconnected and left you to die, is to gloat. And it's rude.)
Luckily, the team we played tonight was from our server (Zuluhed) and belonged to a guild that "fancies itself a serious raiding guild, so they're probably already pretty cocky" according to my good friend and our guild's new raid leader. (See, our guild is interested in being a raiding guild, and we're very good even though we're relatively new. We work together very well. But we aren't cocky or superior. We're friendly, encouraging, and won't associate with anyone who is unfriendly or disparaging. We have real life standards.)
So when this moron paladin tells us to just give up, and his friend says "Hey, they're on our server," I was happy at the chance to /ignore my fourth person on Zuluhed. And I did. With a vengeance.
I only wish I could ignore everyone who's a jerk in arenas. Alas. I can only settle on saving up for enough gear to smack them in the balls. With sharp things.
At the very least, Asadd would deserve it for that many spelling mistakes.