In my fairly disorganized life, yellow stickies are too easily lost, and as for software, I try to avoid using my computer as much more than a typewriter and a post office. I rely on my lifelong habit of daydreaming to spin my stories.
If you're a photographer, they give you a camera. If you're a writer, they give you a typewriter. If you're an umpire, they give you an unseen object and they call it a strike zone, and nobody seems to agree with you no matter what you call.
When I was very little, four or five, I did comic strip drawings, so my first novel had no words. I couldn't write and thought adult handwriting was a mysterious scribble. When I was 14, my grandmother gave me a typewriter and I started writing in a different way.
Harper Lee and Truman Capote became friends as next-door neighbors in the late 1920s, when they were about kindergarten age. From the start, they recognized in each other "an apartness," as Capote later expressed it; and both loved reading. When Lee's father gave them an old Underwood typewriter, they began writing original stories together.
I was living in a large apartment with no furniture, just a typewriter, and because I had nothing else to do with my time, it made me take my writing seriously.