Following writing prompts given in writing contests is a great way to kick-start some great ideas.
It lets your mind free associate, and provides a springboard to dive into a sea of ideas and images, and then acts as an anchor which keeps you grounded in your association of ideas.
I sometimes pick up writing prompts from random contests, often without even participating in them. I start writing, working on the ideas and images that strike me at that moment, just to see where they would take me.
And sometimes, a writing prompt comes from another blog, like this one.
Works well, especially when I am tied up in that bane of all us writers, the infamous writer’s block!