I used to be terrible at talking to people (not saying I'm amazing now
) but my Uncle needed help with a project of his that required talking to people, and I was very intimidated. Buut, after just steeling my mind and talking to one person, everything else was pretty easy, there were literally thousands of people (like a Fair, so not at one time) and I talked to a lot of them about the same thing over the course of probably 8-12 hours. It was amazing, in that one day I had improved more in that regard than years elsewhere. I'm not saying you have an event you can do this, but I can promise you after talking to that first person, everything else will be much easier, just make up your mind that you have to do this, what's the worst they'll do? Tell you no probably, that's a occupational hazard, do your best!
Also, people loove compliments, it's a big compliment to want to capture someone on film/"digital film" so tell them why, say they have gorgeous eyes or something, let them know what it is about them that makes them worthy to be captured instead of someone else
Hope it it helps!