Have you ever been to an important gathering, took photos hoping to document what happened with beautiful photographs, only to discover later that your pics just don't tell the story?
That's a real disappointment most of us have experienced whether we used a phone camera or a “real” camera.
Back in film camera days, getting the shot right in the camera was vital! Unless we had access to a darkroom and processed the film personally, we got what we got and that was that!
Today it is much easier since, to a point, we can see in real time what the images are. So this isn't about settings or technical camera stuff; this is about how to be sure you capture images that tell the story you want to remember. Following is a list of things to do and not do:
Make sure you get pullback photos that show how the venue looks. What is the atmosphere? Is it casual or Professional? Indoor or outdoor? How many people are there? How are they interacting?
If you're using a wide angle lens, try to place people within the frame away from the edges so they aren't distorted. If you “pose” a large group of people, place then in a semicircle, not a straight line. I won't tell you all the reasons why this works, just know that you'll be happier with the resulting photo. (Go ahead and test it. If you don't have people to work with, set up chairs or something else inanimate, first in a straight line, then in a semicircle. Take a photo of each, download to your computer, and see which one is more pleasing to the eye.)
Take closeup photos of specific things. Use a good optical zoom lens or “zoom with your feet.” Walk closer. (Digital zooms make things closer by dropping pixels. You'll end up with a pixelated photo.)
Be sure to get photos of people so that they are recognized. Get close to them. (Stay out of their bubble of safety, though. Hopefully you have a longer prime lens or good optical zoom lens that will permit that.) A good rule of thumb is to fill at least a third of the image with the person. You'll be cutting part of them off, so pay attention that you don't do that at a joint.
If food is part of the event, give people the option to swallow or put down their drink before you photograph them close-up. No one enjoys being ambushed by a camera when their mouths are full. The polite thing is to ask if you may interrupt them for a second. And then honor that second; get the shot and move on.
Don't get so hung up on the technical side of photography that you miss important shots. And don't turn into a photographer stormtrooper. If you know the way a person is standing or sitting will be unflattering in a photograph, move yourself to get a more flattering image. Don't intrude on their pleasure in the event.