I found very few performance-specific photography guide posts when I was looking online to get guidance from other photographers when I first started to take photos. So, I am going to detail the basics of what you will need for performance photography for stage productions.
First, you will need a solid lens that fits your needs. I used my kit lens when I first started but shopped for older used lenses and got a lens with a wider zoom range to accommodate my needs. The important thing to remember with your lens is to make sure it works well with the space and your shooting style. If you like to capture wider shots, you will not need to zoom in as much if you are able to position yourself well in the theatre. Vice-versa, if you prefer to get individual shots or tighter group shots, you will want either a lens with the focal length to support it or a close shooting position (even going backstage +if you are allowed, just be careful of lighting equipment and be sure to listen to the stagehands).
Next, you will need a good understanding of your "exposure triangle." To get that shot with minimal editing, you will need to make sure your triangle is well-balanced for the unique lighting of the production. I have found it best to minimize adjustments made to this triangle so I can react in real-time and change only the shutter speed. To make that happen, though, your aperture needs to be as wide as possible, and your ISO needs to be able to span the darkest and brightest the stage will be at any point while minimizing under- and over-exposed images that require more editing.
The last thing you will need to do when starting is practice shooting moving targets to better read when you should shoot. If you photograph live productions and stage performances, you will be capturing moving targets that will not wait for you to get the perfect shot. If you have a chance to do a photo call, you can take a bit more time to ensure you align a shot well and expose it correctly, but such a thing is a luxury in the world of live performance photography. Growing more accustomed to how movement can be predicted and learning the shots performers love is helpful for any photographer branching into live performance.