What should you wear for a photo? What should you wear when giving a presentation? You should wear pretty much the same thing. Solid simple fashion that does not distract from your main message and your smile.
So you're at an event and from across the room you spot a photographer. What do you do? Your hair is not the best, that's even if you have all of it. You really don't want to be photographed. Why is this guy photographing you? You're not a model. You're just here to network have a drink and tell a few stories.