Late fall is the slowest time of year for me. It's the offseason. I am sure portrait and wedding photogs have a similar situation right after the holidays. Most trades and service providers have a lull sometime during the year. What do you do in the offseason? Sure there will always be photographic opportunities, and I still seek these opportunities, but with the trees bare, color vanished, and no snow in the forecast, opportunities are scarce. I like to catch up on bookwork (prepare for tax season), make new goals (reevaluate old goals), I take a look at my business plan, (revise if needed) read and learn about new technologies and techniques, revisit old images. Update website and blog layouts. I will also go through all my gear, (cameras, tripods, HDD, misc. accessories) and make sure everything is working properly, cleaning out dirt and grime, sending my camera into the service center for an annual check up, etc... I want all my gear to be working flawlessly. Keeping things in the proper working order makes photography a more enjoyable experience.
One of the most important things I try to accomplish is to study some images of fellow photogs, and continue to learn from the photographer community. Look at what images work and why, and look at images that don't work and why. This helps me become a more polished photographer. I will be able to "see" the image more easily, compose quicker, notice things that I didn't notice before, learn what light and conditions work, and why they work. Asking "why" is very important!
I also begin planning on what locations I want to photograph next. Planning trips, taking note of what images I want to make in the coming year. So in reality my offseason is actually busy preparing and planning, so when the moment comes, I will be ready!