(Most of this stuff links offsite - but may be helpful to others, not just the OP.)
Science fiction isn't just about being in space, meeting new and interesting life-forms, nor is it about "Pew-pew-pew, BLASTO!"
Before writing, decide what kind of science fiction you want to write: Wiki Catagories.
Here is a few tips, here are some more.
The last and best science fiction book I have read was: The Forever War. I mention this, because to me it is a great example of logical and rational thinking of consequences. To me, this is just as important as world building, and/or research. Basically, my rule of thumb is: 'Everything you write in SF will be poured over by people much smarter than yourself." So, no matter how the science works (or doesn't work), you can "cheat" by remembering everything has a consequence, which must be both logical and rational. Want to have a ship 'magically' teleport from one side of the galaxy to the other? What is the consequence for a 'technology' being able to do that, for:
A) the society and culture responsible for using that 'technology'?
B) the design and operation of the vessel which uses it?
C) the characters in your story? (whether they are proponents or discontents for the 'tech'.)
You see, unlike most of the genre stuff, SF should be more well thought out than any other genre. Otherwise, readers become suspicious you're blowing the proverbial air up their butts. At least, that's been my experience! :)
Good luck with the story!