In Zen in the Art of Writing, Ray Bradbury explains how he went from a struggling young writer to a more prolific and original one. He attributes his evolution to one simple practice: 
“I began to make lists of titles... These lists were the provocations, finally, that caused my better stuff to surface ... The list ran something like this: THE LAKE. THE NIGHT. THE CRICKETS...”
“...similar lists, dredged out of the lopside of your brain, might well help you discover you, even as I flopped around and finally found me. I began to run through those lists, pick a noun, and then sit down to write...”
In college, I bought a book called 14,000 Things to be Happy About. I used it for prompts. It was a decent tool, but the list was not my list.
Bradbury encourages everyone to make their own list:
“I leave you now at the bottom of your own stair, at half after midnight, with a pad, a pen, and a list to be made. Conjure the nouns, alert the secret self, taste the darkness ... If you speak softly, and write any old word that wants to jump out of your nerves onto the page... Your Thing at the top of your stairs in your own private night... may well come down.”
He’s invoking imagery from one of his prompt-inspired stories entitled The Thing at the Top of the Stairs.
I’m finally making my own list. I bought a Rolodex at a thrift store, and I’m writing statements on the cards. When I go to make something, I’ll flip through the Rolodex and choose a card.
Here’s a painting I did using this method:

Chutes & Ladders - 18x24 in / Posca Paint

My Rolodex and the card that inspired the painting.