Ok, it's June 1965 and the NBC television network comes to you, (because you just happen to be in 1965 and American network TV executives just keep turning up at your door), wanting you to take control of it's new science fiction show after the death of it's creator in a freak lightening related accident.
It's just after Star Trek's second pilot has been ordered and you're in charge of making the thing, and unless you're totally incompetent you should be able to get a firm order for a series. However you still have to work within the restrictions of 1960's American TV, meaning you can't just cherry pick the best bits of future Trek or future sci-fi and think 60's audiences will accept it like 90's audiences. You have to make something that sells and sells well enough to get renewed.
So how do you start one of the most notable television science fiction francises of the 20th century?