I have to do more close research and fact checking for the science fiction. This is not however to say that writing good fantasy does not involve doing good research.
As far as the writing goes, I started telling stories as soon as I could talk, and started writing them down as soon as I could string words together.
I did not want to write a story about the invasion of Earth, so I had to create a race capable of living nearby, which meant to either on the Moon, on Mars, or on Venus. I picked Venus.