Clear the gutters before the first freeze
Gutters clogged with the last of the fall debris hold water that then freezes solid at the first hard cold snap, and ice sitting in a clogged gutter is heavier and more likely to pull hangers loose than water that drains freely. Clearing gutters before the ground freezes is one of the simplest things a homeowner can do to head off winter gutter damage.
Check the attic for air leaks
Before the heating season really gets going, it is worth a look in the attic for obvious gaps around the chimney chase, plumbing stacks, and the attic hatch, since those are the paths warm air uses to escape into the attic and start the ice dam cycle. Sealing what you can reach yourself, and having the rest addressed professionally, pays off directly in fewer ice dams once the deep cold arrives.
While you are up there, check that insulation has not shifted or compressed to the point of leaving thin or bare spots, particularly near the eaves where baffles need to stay clear for the soffit vents to work.
Inspect the roof from the ground
A pair of binoculars from the yard can spot a lot before winter: lifted or missing shingles, damaged flashing around the chimney, a sagging section of gutter, or granules built up at the base of a downspout, which can indicate a roof shedding more material than it should. Anything that looks off is worth a professional look before the first snow rather than waiting until spring.
Trim what could fall on the roof
Branches hanging over the roofline collect ice and snow weight through the winter and can snap under that load, taking shingles or a section of gutter with them. Trimming anything overhanging the roof in the fall removes one more variable before the season's first heavy snow.
It is also worth checking that nothing has grown into contact with the roof edge or the gutter itself, since constant rubbing wears through shingle granules and gutter finish over time.
Know the plan for a bad storm
Before winter sets in, it is worth knowing where to reach a roofer if something goes wrong in the middle of a cold snap, since roofing emergencies do not wait for convenient weather. Having a working roof rake on hand for after a heavy snowfall, and knowing not to walk on an icy roof with a hammer to break up a dam, are the two pieces of practical advice that prevent the most damage between now and spring.