Keep in mind, you should shoot a film within your means. This is very important for indie filmmakers. Everything is a lot harder than it seems, trust me. And if you want it to be taken seriously, then keep in mind your ages and what you are capable of. The first couple years of my own shooting I only made videos where it is plausable for the characters to be young (ex. murderers, drug overdose, etc). We never tried to make an epic space opera, simply because it wouldn't be the product we wanted it to be.
Not to deter you from your dream, but trust me, it's so much easier to start simpler and build your way up. Try writing and shooting a short film where it needs NO SPECIAL EFFECTS. Maybe no more than three locations. Two or three characters MAX, and their interactions.
Use a free program like Celtx (Google it) to write a script roughly in the same format as film (there's way more to it, but it's a good start).
Film is a visual medium, tell the story as much visually as you can. Audio is just as important, but the visuals should be able to tell the story on their own, not necessarily in obvious ways. Different elements can tell the story through their subtext. For example, in the Matrix, whenever they went into the Matrix, they gave it a subtle green hue, and detailed the sets with as many grid-like patterns to emphasize the artificiality of it.
Also, watch the show "Film Riot". You can find this on Youtube. This show is immensely helpful for any amateur filmmakers, and serves pretty much as a pre-Film School. Trust me, I know.
Just remember, start out with something of quality, but smaller. Believe me, that will be more than enough if you really want to pull it off. Aim for 200%, you'll be lucky to come back with 90%. This is how it always goes.
ALSO: Have fun.
