What do I need for my first Twitch stream?

What do I need what should I do in my first stream?

You have to decide for yourself.

Working microphone
A recording device best OBS can be found at Twich you just had to download it
If you want to have a camera you had to get one without it
Stream should be fun.

later you can expand more and more. It is important to talk to the chat or to talk in general - that goes down well.