Batteries in the cold
Two spare cells live in an inside pocket now. At four degrees a full battery gives me barely forty frames, and the camera lies about how much is left.
On not buying a filter holder
I wanted one for eighteen months. What actually improved the pictures was a heavier tripod head and the patience to wait out the wind, which costs nothing and fits in no bag.
Shutter drag on wet asphalt
Rain is not the problem, reflections are. A two second exposure turns every puddle into a mirror of the sodium lamps, and the whole frame goes orange. I now underexpose by roughly a stop and bring the shadows back later, which keeps the highlights on the water from clipping.
The other lesson: bring a cloth. Every twenty minutes the front element collects enough drizzle to soften the corners, and it is invisible on the back screen until you are home.