As a raid leader, the way you give instructions to your team during a fight is very important. You need to be concise, timely and sounding like you are in control. It is assumed everyone is gathered on some kind of voice service for the purposes of this discussion.
What to say
Something I learned in childcare many moons ago was this: Tell a child what they can do, not what they can't do. For example "Don't stand in the sprinkler" leaves a child confused as to whether that order applied to them, and if it did what they should be doing instead. Compare this to "Childsname, go to sit on the step", which has the trigger word of the name, so the child knows to pay attention to the next phrase, and has something they can do which happens to have the flow of effect of removing small child from the sprinkler and thus you not having to deal with a cold, wet, soggy child when you are out and about. It also has the added benefit of being a positive instruction, not a negative one. Which means the child will feel good about completing the instruction as opposed to bad for being told they are doing something wrong.
In WoW terms: "Don't stand in the bad" vs "Brang, run to the star"
Use absolute terms when instructing directions, never relative terms. A great example of relative terms is saying "Move to the right" when you are the tank, facing the raid. So, which right? "NO, NO! MY RIGHT NOT YOUR RIGHT!!" Even using compass points are not fixed enough, how many fights are in round, enclosed rooms? How many times have you been turned around and not realised it?
Absolutes are things which are fixed no matter which way you are facing. Things like doors, patterns on the floor, stairs, engineering smoke flares even raid markings are absolute. You will note I have pointed out all things that are visible on the screen, that you can do a quick spin around and easily see. Someone with a raidmarker on their head might move around, but the marker itself is unique and very visible - which makes it an absolute direction when called. For example "Stack on star", "Run to the stairs".
Promoting a guild jargon will also help. For example, before the fight, set up trigger words which mean something in each fight. "Brang, DS!" when called by the tank to me means use my Divine Sacrifice cooldown now. I also like to your catchy phrases (as you may have noticed in my strat pages). No one cares that the name of the debuff on the tank is Curse of Torpor, they only care about this "MageB, Decurse!" Prior to the fight, you will have allocated MageA the job of decursing the tank, but they ate floor dust so quick reprioritization needs to occur. The actual process has already been assigned, the call is just that - a trigger to cause an action. The shorter the trigger, the faster the reaction.
A really good example of this is in BQL, organising bites is a nightmare, but a quick call like this "Biting Brang" makes it clear to all that someone (it doesn't matter who) has decided to give the Essence of the Blood Queen to me and no one else should try to do the same thing due to mechanics. But saying all that is a mouthful when all you need is 2 words! It's a vampire, vampires bite people and suck their blood! So, of course you are going to use the term "bite".
Using pithy descriptions of things on screen helps too. Trying to find one syllable descriptive terms will help shorten your calls on vent and make them punchier. For example "ADDS!" or "WHELPS!" or "BALLS!" or "WORMS" or "FIRE" or "RUN!" or "STACK" They are all trigger words for a more complex action defined by circumstance, and you will have told everyone what that complex action is before the raid. Your call is just to make sure it happens when you expect it to. The classic line everyone quotes, but is actually a very good example of this is "Many whelps, left side, handle it" While I don't like the use of the term "left" the rest is short punchy and tells the raid what needs to be done. The task had been allocated prior to the raid, people knew who were supposed to be handling whelps. The call went out, they did their job. It was short, and to the point and used pre-set key words to trigger a more complex action.
Instruction vs Warning
Now that you have some idea on how to generate your calls, we need to look at differentiating the two major types of calls used in raids Instructions and Warnings.
Clearly, instructions are imperatives "Do this" "Run there". Imperatives are usually used to either make changes or adapt to mistakes with the strategy.
Warnings are phrases you use to get people in the right frame of mind to action something in the future. "Ability in 10s", "Get ready", "Incoming", "Pulling"
Some phrases you use as a raid leader are combinations of the two. "aaaaaaAAAAAAAND GO!" The first word is a warning, in combination with a imperative "go". A warning combo strike like this is used generally to ensure that no one else is talking on vent at the time, and everyone needs to pay attention - that the action indicated by "go" is the single most important thing that needs to be done at that time.
Most raid leaders will use a warning phrase in combination with an instruction phrase at the time the action needs to occur. "Ability in 10s" ... "ready to run" ... "RUN!"
You can have all the theory in the world, but if you yell instructions like a drill sergeant, or are soft and timid like a mouse on vent, don't expect people to always follow your lead. Your voice is your whip, chain and carrot. With your voice you can cajole, order, beg and prepare people just with inflection.
The one thing you want to be as a raid leader is Calm. You need to appear in control even when everything has turned to shit. Never "yell". Talk loudly and firmly. If you keep instructing people and using imperatives, people will continue to do what you say. Don't ask questions, don't have discussions. Have a wide vocal range - use every inch of your range. Don't be a monotone. Be reasonable, listen to feedback, but stick to your decisions. Once you make a call, stick to it, right or wrong and be confident. All you have is your voice and you have a lot to convey in it.
Smile. No really, smile. You will sound different when you talk with a smile on your face to talking with a frown and the human ear is well attuned to hear this difference. Different muscles are activated and the shape of your throat and mouth is different as well as a whole bunch of brain chemistry that happens. Try it! Your mood will affect your team. So, force a smile onto your face while raid leading even if you want to reach your hand through the screen and murder each and every one of your guildmates.
Vent has a record and playback facility. If you want to experiment, I recommend recording yourself and playing it back. Play around with saying the same phrase in multiple ways and see how you feel.
Well, that should be plenty for you to be going on with. Always always always ask for feedback from your