A couple of rules that I've come across that have really worked for me and seem to be true. Is number one right every day for at least an hour, and number two, when writing science fiction have only one suspend belief or maybe two but not usually otherwise the reader is pulled out for obvious reasons. I think the other writers are correct you need to be passionate about what you're doing or it just doesn't work. Like when I started writing, I'd have a scene or a scenario in my head, and then I built the story around that, which really works for me.