I was reading a forum thread where people talked about watching your threat meter, but mine isn't visible and I don't know how to show it.
The default shortcut is Control and the T keys or Ctrl-T for short. This on default UI becomes a bubble with crossed swords, the number inside is your threat level and the amount of fire in the background is the % towards having aggro. If you are not a tank, any number above 75% is a danger zone where you can rip as chances are in a group you are #2 on the hate list and in a raid you are within the top 7 positions (the top 3 should almost always be the 3 tanks in the raid).
