For the novels I wrote before selling anything, I didn't outline much. I had a vague idea of the story.
The benefit of this kind of outlining is that you discover a story's flaws before you invest a lot of time writing the first draft, and it's almost impossible to get stuck at a difficult chapter, because you've already done the work to push through those kinds of blocks.
When I was a teenager, I got into SF, quite heavily, and that too has had a major impact on my writing.
