This is going to sound wishy-washy and vague, but it's true:
Find your style.
I'm one of about three people is our guild who leads raids on a regular basis and we all have slightly different approaches. Some differences include how much carrot vs. stick is used, how much input from others over vent is acceptable during raid time, how much fun chatter is acceptable, and whether/how much individual people are called out for errors in vent vs in private tells.
There are a number of approaches that work, you just have to figure out what is a good fit for your raid and your own personality. It will take some experimentation with different styles, and you will make some mistakes. That's okay, you don't become a good raid leader overnight. I've only been doing it for a couple months myself and still have a lot of room for improvement.
Since I've been giving lots of vague high-level advice, one practical tip: get a couple people to help you with administrative details. First of all, loot. Get someone else to handle it, you've got more important things to worry about. In our raids, we also have someone who in charge of managing the raid make up. They get the groups set, make sure the right people are waiting outside the instance, and make substitutions when needed. Having a separate person doing that is very nice as it allows that stuff to be taken care of while you're leading trash, reducing downtime.
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