Black nail polish is very popular for the fall. I like to do a deep color but not black. This is my favorite. It's Wet n Wild "Nocturnal" and it's a deep purple color.
I also like to wear a deep burgundy in the fall. These are two of my favorites and they look virtually the same. That's Sally Hansen "Flirt" and OPI "Plum Full of Cheer".
Purple is my favorite color and I love to wear it on my nails in the fall! The above is two of my favorites and they are pretty much dupes for each other. That's Sinful Colors "Let's Talk" and Wet n Wild "Buffy the Violet Slayer".
Sometimes you get tired of the dark colors in the fall and you want a bright color but nothing too summery. This is perfect for those days. "Tuscan Sun" by Revlon.
And then of course you need a great nude color. This is a gray nude, perfect for fall. It's called "Dove' by Zoya.