I've come to realize how difficult it is to only have light and nothing else... A reflector is your best friend, and something or someone to hold it in place.
Dirty windows are great. Watch the direction of light carefully to judge shadows.
Have something warm and comfortable for your model to wear between frames that doesn't leave marks. Take breaks.
For me gross overexposure has worked and then pull develop, to reduce contrast.
Have a very flexible tripod that can get very close to the ground and high up without getting rickety.

That's all I can think of off the top of my head.

- Thomas