Pen and paper., Keyboard and computer. Writing materials don't matter. It's not the way you get it down, but what you say and how you say it. Don't be afraid to feel. Don't be afraid to tell the truth. And above all, don't be afraid to tell a lie! After all, that's what fiction is all about!
Research. Research. Research. Make it real. Make it right. Even SciFi has to be believable. And readers want to believe...they really do.