The more willing you are to travel at a moment's notice, the more opportunities you can access. Day jobs will limit travel, so will mortgages and car payments. Photojournalist Lynsey Addario recently wrote about being 7 months pregnant while on assignment in Gaza. I deeply admire her bravery and commitment to her work, but I imagine many photographers aren't willing to make such compromises. Consider your lifestyle, and how much time you're willing to spend away from home. As for myself, I'm a long-term digital nomad traveling with a suitcase and a backpack and an open mind. Being available and flexible has made a monumental difference to my career.
The other challenge is to scout for and find the locations for the photo shoots; locations that provide a "badge" of authenticity to the resulting photo films. In the the case of The Girl of Nanjing, it was the water town of Qi Bao near Shanghai....and in the case of The Legend of Hua, it was the water town of Xinchang' at some distance from Shanghai as well...while the backdrop to The Songstress of Temple Street was Hong Kong's famous Tin Hau Temple and the Canton Singing House.
The Lower Omo River in south west Ethiopia is home to eight different tribes whose population is about 200,000 and it is there that they've lived there for many centuries. The tribes such as the Daasanach, Kara (or Karo), and the Mursi live along the Omo river and depend on it for their livelihood. The annual flooding of the Omo River feeds the biodiversity of the region and guarantees the food security of the tribes especially as rainfall is low and erratic.