She's right. Once I've outlined a novel, I go and peruse the internet for photos of actors who come close to how I envision my characters will look. Then I print them out, and have a little "posterboard" of characters close by. It helps me see them side by side and visualize how they'll interact. (Usually, they just tell me what is going to happen, but that's not something I like to tell non-writing people. Because it makes me Schizophrenic. ;-) Which I'm not.
Some writers write by the seat of their pants, and go with it. No linear plot, just bits and pieces. Not me. I have to have a "vision." I have to have that "movie" in my head. Sometimes it's there without any effort. Sometimes I have to work for it. Sometimes Life gets in the way and I have to set the popcorn down and press "pause" until I can get back to it.
But I always come back. ;-)