Getting started is the hardest part. How do you build something from nothing? One day at a time. However, I'm working full-time, occasionally 7 days a week, and yet I managed to finish writing a novel, format and publish it to Kindle. Now comes the dreaded part: marketing! I can come up with original, likeable characters and tell fun and imaginative stories. For me, that's the easy part. Making the world aware that I exist is quite another matter.
Science fiction adventure/space opera isn't too tricky to write, if you have the practice. A little science research and it should actually be truer to current theory than some rather familiar science fiction franchises out there. But the important thing is that you love what you do: passion will show every inch of the way. If you don't really care for the art, that will show too (in oh so many ways!)
My debut novel, Sector Storm, is now available in print-on-demand. That might help with reaching readers who either do not own a Kindle or do not like reading a novel in eBook form. As for marketing, I've been asking many of the large Amazon reviewers to take a look. One so far has at least expressed an interest, but warns it may take a while to get around to it.
“You must keep sending work out; you must never let a manuscript do nothing but eat its head off in a drawer. You send that work out again and again, while you're working on another one. If you have talent, you will receive some measure of success - but only if you persist.”
― Isaac Asimov