Strategies

Arena play is vastly different from other PvP in the game.  Before the battle starts, you have 1 minute of arena preparation, where spells cost 0 mana/rage/soul shards, and this is the time to buff up your team.  You also won't know the makeup of your opposition until they come up on your screen (although on smaller battlegroups you can often guess depending on how long you have queued for). 

The two different arenas present different strategy opportunities.