Boots and Booties! I live in nothing else all through the Seattle fall and winter seasons.
I never wear rainboots; I find them very uncomfy to wear indoors and I do not like the hassle of carrying shoes and switching into another pair. I recommend several pair of flat boots or booties that are wide enough at the calf to tuck skinny jeans or leggings into. I also wear my Aquatalia boots and booties constantly, although these are pretty pricey.
Skirts are OK as long as they are pencil or otherwise not a skirt that will blow up in the wind. I have a long tube midi skirt I am wearing today with booties and tights. I usually avoid wide hems (i.e. bootcuts) in the rain, although yesterday I wore trousers and now they need to be cleaned. )-:
I like hats, but in fall I find ear muffs more practical because while it windy and cold, it's not so cold that I need to bundle my head up and I just want to protect my ears from freezing off without my head sweating.
I have a long neck, so I usually wear a scarf when it's raining - a light weight one if it's not freezing out, or a cashmere one if it's cold.
I use an umbrella -I have one that opens AND closes with a button on the handle and it is beyond convenient because I don't need two hands free to close it when going indoors.
I find leather gloves really important - my hands get very cold and when I have to hold an umbrella and can't put them in my coat pockets its important to have wind-proof gloves.
I also have a trench coat but since I use an umbrella I don't really feel the need to wear it every time it's raining unless it's really pouring out (which actually doesn't happen THAT often in Seattle - usually it's more of a nasty, windy drizzle that blows everywhere).