Live recording is a delicate procedure and the way you go about doing it depends a lot on your environment. The type of venue, how much authority you have, the type of music, the sound equipment, the reasons you are recording. All of this and more must be taken into careful consideration before even starting to record.
SweetWater.com has a very thorough article on the fundamentals of live recording. That will be linked here and it is definitely worth a read.
The first thing to think about is what you want the final product to be. Are you recording for a smooth, polished live album? Do you just need the audio for a well produced live video? A quick social media post? Thinking about these questions will dictate the equipment you use and how much time you spend on this project.
The process for getting the audio does not have to be a grand set up of a dozen microphones placed all over the music area. For example, if you need a decent quality stereo recording and are under a short time limit than a Zoom H4n microphone will get the job done. This is a good way if you need the audio for a live video of the band. After using the H4N then the rest of the work is all mixing.
The most important thing to keep in mind when mixing live audio is to be careful not to distort the audio. It is very easy to add too much gain on a live recording or mix the low ends too high. SoundOnSound has a very in-depth article on mixing live recordings. That article can be found here.
The most important things is to be in good communication with the band and venue so they know what you are wanting to attempt and can help as needed. Understand what your role is as an audio gatherer. And as always always expect the unexpected.