All of us get invited to parties and events. If the hosts know you are a photographer, they may think, "Hey, he’s got a nice camera, let's ask him to take some photos." I see quite a few photographers at events with their flash units on top of their cameras with the latest modifier on it. I always chuckle a bit because I've always hated how those photos look. They're mostly the "Everyone say cheese" variety. Instead, go without a flash and use the available light in the venue. Sure, it may be horrid, dark or yellow or green, but make do with what you've got. Look for authentic expressions and interactions.... Pump up your ISO, take it off Auto and look for a story.
Light, expression, environment.
My friend Ken and his wife had a party for their new daughter. And even though they never asked me to photograph the event, whenever a close friend invites me to an important event, I try to capture a few images for them. So as I watched him walk around the venue with his pride and joy, I noticed that when he faced his daughter toward the Western windows, this beautiful light would frame her face. So I simply placed myself in a position next to one of the tables so I could capture her awash in beautiful light as she gazed over her father's shoulder. Some photographers may ask someone to stand in good light and I can understand that method. But my preference is to just
let it happen organically. Light, expression, environment.