Ever written a science fiction poem?
Get ready to start.
Let's start with a basic idea of what science fiction really is and what it's not.
One basic rule to start with is: science fiction is not fantasy with robots (Sorry, Star Wars). What is it then? For the sake of this exercise, let's agree that it's the basic asking of a question starting with "What if...?"
So we should start with a basic question that hopefully leads us into something more complex.
A couple quick examples you may or may not be aware of:
"Do Androids Dream of Electric Sheep" by Phillip K. Dick starts with the question "What if Androids were as emotionally complex as humans?"
"The Time Machine" by H.G. Wells starts with the questions "What if humans evolved physically along the same lines as we're evolving socially?" (It's all about the Morlocks and the Eloi. The Time Machine's the MacGuffin)
Orwell's "1984" starts with "What if government valued power over choice?"
Everything else spirals out from there.
So, start with a basic premise and see where it takes you. What if our insecurities manifested themselves as weather events? What if our inner voices could be heard... all the time? What if all the animals on earth were actually aliens, watching over us?