There are two things you have to think about when trying to nail exposure using manual mode.
The first is the exposure itself, and the second is how the photo looks
Both of these concerns are addressed through setting your ISO, Aperture, and Shutter Speed.
What I’m not going to do here is tell you what settings to use. Photography doesn’t work that way. Instead, we’re going to talk about the process, because if you have a solid process, then no matter what situation you find yourself shooting in, you’ll be able to nail your exposure and get the perfect photo.