this week, I plan on going on my first shoot. I'm going to be in New York City doing portraits (headshots) outside with random people I might meet in the streets. My backdrop is going to be a yellow poster board, and I am using an OM-4. My question is what other equipment would I need in order to get the best quality and best tones? Also, which film would work best? I was thinking of using portra 160nc...also, would a direct flash benefit me?