For the moment I am going to address the issue of mindful gearing up for winter from the gutter line up.
Gutters should be cleaned of Fall leaves and downspouts checked to make sure they carry water to where they should. Great care should be given to securing the ladder with a rope or bungy chord to a gutter strap. The ladder must be firmly and squarely set upon ground that is not slippery. If you are not a professional it makes sense to have someone with you holding your ladder. If you don’t follow this advise, remember that my Father died falling from a ladder he leaned over too far from.
Gutter straps and drainage should be checked. You may never achieve perfect drainage with your current gutters (or possibly any gutters, depending upon the settling issues of your building).
Flat roofs cause the biggest problems during the winter. Ice and snow freeze and thaw a lot during the days and weeks of winter. Water does not drain or evaporate like in the warmer months. Projects like porch posts or vents often find the caulking around them contract a bit from the cold and loose the tight bond required to keep moisture from penetrating.
Remember that water is the subtlest of elements. It can penetrate that which the eye cannot see. It seeks the lowest level. Rare is the flat roof the drains perfectly. Portions of the membrane may have become porous. Seams may have lost their sealing power. Projections may need their flashing upgraded.
This is worth starting out with if you really want to prepare yourself for a good relationship with your roof system over the years.
With binoculars or from a secure ladder position scan the shingles of your roof to see if any have blown away, cracked, slipped, lost their power to deflect water, or find holes from popping nails, fallen branches, squirrels, whatever.
Also check the projections through the roof, especially the roof/wall intersection at chimneys and dormers. Valleys and roof projections like vents should be checked for integrity.
I wrote this last year and still find it useful.