Effective Communication During a Raid
Ventrilo is primarily used as an efficient way for the Raid Leader to instruct the members of the raid on how to proceed. As such it should generally be kept clear except in certain specific circumstances. Always ensure (by testing before the raid if necessary) that your microphone is at an appropriate distance from your mouth and that you are speaking clearly. If you are unable to speak on Vent then you should set up macros in advance for events in encounters you may face at the touch of a button. For example, a macro that yells "Mertissielle is in an ice block" on the Hodir fight is easier and allows the raid to respond quicker than typing it out in full. If you suspect you may not be able to speak then it is essential you research the bosses and set up appropriate macros for these events ahead of time.
It's natural to say "I" as it is the way we would ordinarily speak, but in a raid not everyone will know your voice or necessarily be able to distinguish it from others. While this may be more the case when there are newer people in the guild, you should always assume that people won't know who you are and make every effort to speak about yourself in the third person - for example, "Mertissielle has aggro" is much clearer than "I've got aggro".
Announcing your death:
All raid leaders use some form of raid frame UI and can see the health and status of the entire raid. Unless you have been given a specific role to fulfil within an encounter where it is critical that somebody take over, you should always assume that the raid leader is aware of your death and will take necessary steps such as battle-ressing you if necessary. Generally speaking it is tanks and healers who will need to announce their death or other form of being incapacitated, though certain fights may also require DPS to announce their sudden absence, such as people assigned to interrupt on Kel'Thuzad or Priests assigned to use Mind Control on Instructor. If you are not given a specific role to fulfil, you should not announce your death over Vent as it could mean something else goes unheard.
Voicing your frustrations:
World of Warcraft can be brutal at times - you can be unlucky with the RNG leading to you being one-shot or we could wipe on a boss when he would only need one more hit to have died. It happens and it is frustrating but again it is best to keep frustrations off Vent wherever possible. Other people feed on the energy on Vent and if it feels negative the rest of the people listening will feel that negativity too.
Tactics changes or last-minute adjustments:
These should always be at the discretion of the Raid Leader. If you are not the raid leader then feel free to suggest something if you are certain that it won't cause confusion to do so, but always phrase it as a question. Calling for a change of tactics mid-fight can cause confusion and can lead to people taking different interpretations, unsure of whose command to follow.
Most fights will have several raid leaders and they may be assigned to look at different aspects of the fight. If you are not one of them then, like above, it can cause confusion to have a different voice issuing instructions. Far better to save any observations until after the fight than to risk a wipe due to uncertainty.
This is the time to state any observations you've made or suggestions for tactics changes, but you should remain courteous at all times - if someone is speaking, do not speak over them and if you catch yourself doing so you should stop and let them finish before adding your suggestion - having four people speak at once only leads to frustration and a lack of clarity. Remember however that the raid leader is the ultimate decision-maker and if he chooses not to incorporate your suggestion then do not get into an argument or let it affect your performance. If you still think your way would work then discuss the benefits you believe it will bring to the raid after the next wipe.
Effective Communication During a Raid